Resonant cavity micro light emitting diode array device and method of fabricating the same

Abstract

This invention provides a resonant cavity micro-light-emitting diode array device and its fabrication method for optical interconnect applications. It relates to the field of semiconductor optoelectronic device technology. The device includes: a substrate; a first dielectric layer formed on the substrate; a light-emitting epitaxial structure formed on the first dielectric layer; and a second dielectric layer formed on the light-emitting epitaxial structure. The first dielectric layer, the light-emitting epitaxial structure, and the second dielectric layer constitute an optical resonant cavity structure. Photons propagate back and forth within the optical resonant cavity structure to preserve and enhance wavelengths that satisfy the resonance condition, outputting spontaneously emitted light with monochromaticity and a satisfactory light divergence angle.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronic device technology, and in particular to a resonant cavity micro light-emitting diode array device for optical interconnect applications and its fabrication method. Background Technology

[0002] Against the backdrop of ever-increasing demands for computing power in scenarios such as Artificial Intelligence (AI), Machine Learning (ML) supercomputing, and 5G edge computing, copper cable electrical interconnects are approaching their physical limits in terms of bandwidth, power consumption, and transmission distance. Data interconnection between server boards and chips has become a bottleneck for computing power. In contrast, optical interconnect solutions have many advantages in terms of transmission rate, transmission distance, bandwidth density, energy consumption and heat dissipation, integration, and electromagnetic interference.

[0003] Micro-LEDs, with their advantages of small size, multi-channel parallel transmission (slow but wide), low bit error rate, and high integration, provide a new path to break through the bottleneck of traditional electrical interconnects and are expected to support the construction of more powerful and efficient AI hardware architectures that are difficult to achieve with current interconnect technologies. Summary of the Invention

[0004] In view of this, the present invention provides a resonant cavity micro light-emitting diode array device for optical interconnect applications and a method for fabricating the same, which at least partially solves the above-mentioned technical problems.

[0005] One embodiment of the present invention provides a resonant cavity micro light-emitting diode array device for optical interconnect applications, comprising: a substrate; a first dielectric layer formed on the substrate, and a light-emitting epitaxial structure formed on the first dielectric layer; and a second dielectric layer formed on the light-emitting epitaxial structure. The first dielectric layer, the light-emitting epitaxial structure, and the second dielectric layer constitute an optical resonant cavity structure. Photons propagate back and forth in the optical resonant cavity structure so that wavelengths that satisfy the resonance condition are retained and enhanced, and spontaneous emission light with monochromatic light divergence angles satisfying the conditions is output.

[0006] According to an embodiment of the present invention, both the first dielectric layer and the second dielectric layer are periodically distributed Bragg reflective dielectric layers, and the number of periodically distributed Bragg reflective dielectric layers in the first dielectric layer is greater than the number of periodically distributed Bragg reflective dielectric layers in the second dielectric layer.

[0007] According to an embodiment of the present invention, the light-emitting operating wavelength of the light-emitting epitaxial structure is consistent with the reflection operating wavelength of the periodically distributed Bragg reflective dielectric layer; the reflectivity of the first dielectric layer is greater than or equal to 95%, and the reflectivity of the second dielectric layer is 50% to 70%.

[0008] According to an embodiment of the present invention, the materials of the first dielectric layer and the second dielectric layer include one or more combinations of silicon oxide, titanium oxide, hafnium oxide, and tantalum pentoxide.

[0009] According to embodiments of the present invention, the optical crosstalk of each micro-light-emitting unit in the resonant cavity micro-light-emitting diode array device is positively correlated with the light emission angle of the resonant cavity micro-light-emitting diode; the coupling efficiency between the optical fiber and the light-emitting unit in the resonant cavity micro-light-emitting diode array device is negatively correlated with the light emission angle of the resonant cavity micro-light-emitting diode; the monochromaticity of the light-emitting unit in the resonant cavity micro-light-emitting diode array device is negatively correlated with the full width at half maximum (FWHM) of the resonant cavity micro-light-emitting diode; the coupling quality between the optical fiber and the light-emitting unit in the resonant cavity micro-light-emitting diode array device is negatively correlated with the FWHM of the resonant cavity micro-light-emitting diode; and the optical fiber loss in the resonant cavity micro-light-emitting diode array device is positively correlated with the FWHM of the resonant cavity micro-light-emitting diode.

[0010] According to embodiments of the present invention, the light-emitting unit array in the resonant cavity micro light-emitting diode array device is a linear array or a surface array; the wiring method of the resonant cavity micro light-emitting diode array device is multi-layer wiring; the diameter or length and width dimensions of the light-emitting unit are 0.5μm~100μm.

[0011] According to embodiments of the present invention, the substrate includes one or more of a silicon substrate, a sapphire substrate, a silicon carbide substrate, and a gallium nitride substrate.

[0012] According to an embodiment of the present invention, the light-emitting epitaxial structure includes an n-type semiconductor material layer, an active layer, and a p-type semiconductor material layer stacked sequentially, or a p-type semiconductor material layer, an active layer, and an n-type semiconductor material layer stacked sequentially; the material of the active layer includes one or more of aluminum-doped gallium nitride and indium-doped gallium nitride.

[0013] According to embodiments of the present invention, the device further includes: a metal electrode layer formed on the surface of the quantum well epitaxial structure away from the substrate; the material of the metal electrode layer includes one or more of aluminum, silver, nickel, gold, platinum, chromium, titanium, or copper; an insulating dielectric layer located between the p-type semiconductor material layer and the metal electrode layer, or between the n-type semiconductor material layer and the metal electrode layer; a transparent conductive layer in ohmic contact with the metal electrode layer for adjusting the uniformity of electrical injection; and an insulating passivation layer serving as a sidewall protection layer for the resonant cavity micro-light-emitting diode array device for preventing direct electrical interconnection between the p-type semiconductor material layer, the active layer, and the n-type semiconductor layer caused by subsequent evaporation of metal electrodes.

[0014] Another aspect of this invention provides a method for fabricating a resonant cavity micro-light-emitting diode array device for optical interconnect applications, comprising: fabricating a light-emitting epitaxial structure on a substrate, wherein material optimization is performed by etching the sidewalls of the light-emitting epitaxial structure to improve luminous efficiency; fabricating a multilayer oxide of a specific thickness and structure using one or more combinations of plasma-enhanced chemical vapor deposition, electron beam evaporation physical vapor deposition, magnetron sputtering, and atomic layer deposition to form a first dielectric layer and a second dielectric layer; wherein the first dielectric layer, the light-emitting epitaxial structure, and the second dielectric layer constitute an optical resonant cavity structure, and photons propagate back and forth in the optical resonant cavity structure so that wavelengths that satisfy the resonance conditions are retained and enhanced, and spontaneous emission light with monochromaticity and light divergence angle satisfying the conditions is output.

[0015] The resonant cavity micro-light-emitting diode array device and its fabrication method for optical interconnect applications provided by this invention have at least the following technical advantages:

[0016] An optical resonant cavity consists of a first dielectric layer, a light-emitting epitaxial structure, and a second dielectric layer, forming an optical resonant cavity structure. When photons propagate back and forth within the cavity, only light waves that satisfy the resonance condition (i.e., whose wavelength is an integer multiple of the cavity length) can form stable standing waves; other wavelengths are suppressed due to destructive interference. This mechanism significantly improves the monochromaticity of the output light, reduces spectral broadening, and meets the requirements of high-precision wavelength matching in optical interconnects.

[0017] Both the first and second dielectric layers are periodically distributed Bragg reflector (DBR) layers. The high reflectivity of the resonant cavity's mirrors reduces photon leakage and extends the photon lifetime within the cavity, thereby improving the Q value. A high Q value implies a narrower linewidth and stronger wavelength selectivity, further optimizing monochromaticity.

[0018] The bottom DBR mainly serves as a total reflection mirror. The increased number of layers ensures that photons are reflected multiple times within the cavity, enhancing the interaction with the luminescent epitaxial structure, increasing the radiative recombination rate, and suppressing non-resonant wavelength light to optimize the monochromaticity of the output spectrum. Attached Figure Description

[0019] The above-described features, other objects, and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0020] Figure 1 The diagram schematically illustrates the overall structure of a resonant cavity micro-light-emitting diode array device for optical interconnect applications according to an embodiment of the present invention.

[0021] Figure 2 The diagram schematically illustrates a front view of a resonant cavity micro-light-emitting diode array device for optical interconnect applications according to an embodiment of the present invention.

[0022] Figure 3 The illustration schematically depicts a practical application scenario for optical interconnection, comprising a resonant cavity micro-light-emitting diode array device for optical interconnection applications according to embodiments of the present invention, and a coupling and high-speed shortwave detection array of a multi-core optical fiber in the visible light band.

[0023] Figure 4 A flowchart illustrating a method for fabricating a resonant cavity micro-light-emitting diode array device for optical interconnect applications according to an embodiment of the present invention is shown. Detailed Implementation

[0024] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the invention for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0025] In the process of developing this invention, it was discovered that the selection of optical interconnects for future data centers is an inevitable result of multi-dimensional requirements such as bandwidth, latency, energy efficiency, and reliability. However, Micro-LED optical interconnects suffer from two major scientific problems: severe beam divergence and optical crosstalk within the light source chip, and the limitation of bandwidth and transmission rate due to the wide spectral width of the light source chip. To address these issues, this invention proposes a resonant cavity micro-light-emitting diode array device for optical interconnect applications. Specific embodiments are described below.

[0026] Figure 1 The diagram schematically illustrates the overall structure of a resonant cavity micro-light-emitting diode array device for optical interconnect applications according to an embodiment of the present invention.

[0027] like Figure 1 As shown, the resonant cavity micro light-emitting diode array device for optical interconnect applications in this embodiment may include a substrate 100, a first dielectric layer 200, a light-emitting epitaxial structure 300, and a second dielectric layer 400.

[0028] A first dielectric layer 200 is formed on a substrate 100. A light-emitting epitaxial structure 300 is formed on the first dielectric layer 200. A second dielectric layer 400 is formed on the light-emitting epitaxial structure 300.

[0029] According to the embodiments of the application, the first dielectric layer 200, the light-emitting epitaxial structure 300 and the second dielectric layer 400 constitute an optical resonant cavity structure. Photons propagate back and forth in the optical resonant cavity structure so that the wavelength that satisfies the resonance condition is retained and enhanced, and spontaneous emission light with monochromaticity and light divergence angle satisfying the conditions is output.

[0030] According to an embodiment of the present invention, the light-emitting epitaxial structure is the light source portion of the entire device. When an appropriate electrical excitation (such as an injection current) is applied to the device, electrons and holes in the light-emitting epitaxial structure recombine. During this process, electrons transition from a high energy level to a low energy level, releasing energy, which is radiated in the form of photons, thereby producing spontaneous emission light with good monochromaticity and a small light divergence angle.

[0031] Photons generated by spontaneous emission propagate continuously back and forth within the optical resonant cavity. Due to the interfaces between the first and second dielectric layers and the luminescent epitaxial structure, photons undergo reflection and transmission at these interfaces. Some photons are reflected back and forth between the two interfaces, forming a stable oscillation mode.

[0032] During the round-trip propagation of photons, only photons that satisfy the resonance condition can oscillate continuously within the resonant cavity and be amplified. Photons satisfying the resonance condition continuously interact with the luminescent centers in the luminescent epitaxial structure during their propagation, exciting more photons of the same wavelength, thus amplifying the light of that wavelength. Photons that do not satisfy the resonance condition, unable to form stable oscillations within the resonant cavity, gradually escape or are absorbed by the medium.

[0033] After selection and enhancement by the optical resonant cavity, the spontaneously emitted light, which originally contained multiple wavelength components, is filtered and amplified, with only light of specific wavelengths that meet the resonance conditions being significantly enhanced. Ultimately, the light output from the device possesses good monochromaticity, meaning its wavelength range is very narrow, approaching monochromatic light. In optical interconnect applications, spontaneously emitted light with good monochromaticity can reduce signal dispersion and interference, improving the transmission quality and reliability of optical signals.

[0034] In some embodiments, both the first dielectric layer and the second dielectric layer are periodically distributed Bragg reflective dielectric layers, and the number of periodically distributed Bragg reflective dielectric layers in the first dielectric layer is greater than the number of periodically distributed Bragg reflective dielectric layers in the second dielectric layer.

[0035] According to an embodiment of the present invention, a DBR is a multilayer structure composed of alternating stacks of two dielectric materials with different refractive indices. When light propagates in the DBR, reflection and transmission occur at the interfaces of each dielectric layer. Due to the different refractive indices of the two dielectric materials, interference occurs between the reflected light. By rationally designing the thickness (typically one-quarter of the wavelength of light in the medium) and refractive index of each dielectric layer, constructive interference can occur in the DBR for light within a specific wavelength range, thereby enhancing reflection; while destructive interference occurs for light within other wavelength ranges, resulting in weaker reflection. In this way, the DBR can achieve high reflectivity for light within a specific wavelength range.

[0036] According to an embodiment of the present invention, the DBR is composed of a plurality of pairs of "high refractive index layers n" H "and "low refractive index layer n L The "sandwich" structure, composed of layers, has its thickness precisely designed. In any given n... H / n L At a single interface, due to the refractive index difference Δn=n H -n L A small portion of the light will be reflected back, but most of it will pass through. The optical thickness of each layer of the DBR (Dielectric-Resistant BR) is equal to the physical thickness multiplied by the refractive index, and is designed to be one-quarter of the target wavelength λ0, i.e., n H ×d H =n L ×d L = λ0 / 4. When light with wavelength λ0 is incident perpendicularly, the optical path difference of the light reflected from all adjacent interfaces is exactly an integer multiple of half the wavelength. Countless weakly reflected beams from hundreds or thousands of interfaces in the DBR undergo completely constructive interference in the incident direction, superimposing into a very strong reflected beam. At the same time, in the transmission direction, these multiple-reflected beams undergo destructive interference, resulting in a significant reduction in the transmitted light.

[0037] Cavity length L affects photon lifetime and intracavity photon density. Shorter cavities typically have higher photon escape rates, meaning stronger output coupling, which improves slope efficiency: the increase in optical power per unit current increase. However, excessively short cavity lengths can reduce overall gain volume, potentially limiting maximum output power. Therefore, cavity length design must strike a balance between efficiency and power.

[0038] By designing the period, thickness of each medium layer, and cavity length of the distributed Bragg reflector (DBR), resonance can be generated for different wavelengths, thereby achieving high spectral purity.

[0039] According to an embodiment of the present invention, the large number of periodically distributed Bragg reflective dielectric layers in the first dielectric layer indicates that light will experience more reflective interfaces in the first dielectric layer, thereby producing a stronger reflection effect.

[0040] According to an embodiment of the present invention, the second dielectric layer has fewer periodically distributed Bragg reflective dielectric layers, and its reflectivity is relatively lower than that of the first dielectric layer. This allows the second dielectric layer to allow some light to pass through while ensuring a certain level of reflectivity. The purpose of this design is to form a suitable feedback mechanism within the resonant cavity, which can maintain the round-trip propagation of photons and the resonance enhancement, while also allowing spontaneously emitted light that meets the resonance conditions to be effectively output to the outside of the device.

[0041] In some embodiments, the light-emitting operating wavelength of the light-emitting epitaxial structure coincides with the reflection operating wavelength of the periodically distributed Bragg reflector layer. The reflectivity of the first dielectric layer is greater than or equal to 95%, and the reflectivity of the second dielectric layer is 50% to 70%.

[0042] According to an embodiment of the present invention, the DBR is composed of two materials with different refractive indices stacked alternately, and its reflection characteristics exhibit significant wavelength selectivity. When the emission band of the emitting epitaxial structure coincides with the reflection band of the DBR, the DBR can efficiently reflect light of a specific wavelength, while light of other wavelengths is transmitted or absorbed. This matching ensures that only photons satisfying the Bragg condition can form stable oscillations within the resonant cavity, thereby outputting spontaneously emitted light with good monochromaticity.

[0043] The first dielectric layer serves as the bottom reflector of the resonant cavity. Its high reflectivity (close to 100%) effectively limits the propagation path of photons within the cavity, reduces photon leakage, and thus enhances the interaction between photons and the luminescent epitaxial structure, thereby improving stimulated emission efficiency.

[0044] The second dielectric layer acts as the top reflector of the resonant cavity. Its partial reflectivity (50%–70%) allows some photons to be transmitted outside the cavity, forming the spontaneous emission light output after resonance within the cavity. Simultaneously, the remaining photons propagate back and forth within the cavity, continuously interacting with the luminescent epitaxial structure to further enhance light of specific wavelengths. This design balances light output power and monochromaticity, avoiding the problems of excessively high photon density or excessively low output power caused by total internal reflection.

[0045] In some embodiments, the materials of the first dielectric layer and the second dielectric layer include one or more combinations of silicon oxide, titanium oxide, hafnium oxide, and tantalum pentoxide.

[0046] In some embodiments, the optical crosstalk of each micro-light-emitting unit in the resonant cavity micro-light-emitting diode array device is positively correlated with the light emission angle of the resonant cavity micro-light-emitting diode; the coupling efficiency between the optical fiber and the light-emitting unit in the resonant cavity micro-light-emitting diode array device is negatively correlated with the light emission angle of the resonant cavity micro-light-emitting diode; the monochromaticity of the light-emitting unit in the resonant cavity micro-light-emitting diode array device is negatively correlated with the full width at half maximum (FWHM) of the resonant cavity micro-light-emitting diode; the coupling quality between the optical fiber and the light-emitting unit in the resonant cavity micro-light-emitting diode array device is negatively correlated with the FWHM of the resonant cavity micro-light-emitting diode; and the optical fiber loss in the resonant cavity micro-light-emitting diode array device is positively correlated with the FWHM of the resonant cavity micro-light-emitting diode.

[0047] According to embodiments of the present invention, the optical resonant cavity structure described above can narrow the light emission angle and full width at half maximum (FWHM) of the micro-LED. Narrowing the light emission angle of the micro-LED reduces optical crosstalk between the micro-light-emitting units in the light-emitting array during signal transmission in optical interconnect applications, and increases the coupling efficiency between the optical fiber and the light-emitting units. Narrowing the FWHM of the micro-LED enhances the monochromaticity of the light-emitting units, further improving the coupling quality between the optical fiber and the light-emitting units in optical interconnect applications, and reducing optical signal loss in the optical fiber.

[0048] In some embodiments, the light-emitting unit array in the resonant cavity micro light-emitting diode array device is a linear array or a surface array; the wiring method of the resonant cavity micro light-emitting diode array device is multi-layer wiring; the diameter or length and width dimensions of the light-emitting unit are 0.5μm~100μm.

[0049] In some embodiments, the substrate includes one or more of a silicon substrate, a sapphire substrate, a silicon carbide substrate, and a gallium nitride substrate.

[0050] In some embodiments, the light-emitting epitaxial structure includes an n-type semiconductor material layer, an active layer, and a p-type semiconductor material layer stacked sequentially, or a p-type semiconductor material layer, an active layer, and an n-type semiconductor material layer stacked sequentially; the material of the active layer includes one or more of aluminum-doped gallium nitride and indium-doped gallium nitride.

[0051] In some embodiments, the device further includes: a metal electrode layer formed on the surface of the quantum well epitaxial structure away from the substrate; the material of the metal electrode layer includes one or more of aluminum, silver, nickel, gold, platinum, chromium, titanium, or copper; an insulating dielectric layer located between the p-type semiconductor material layer and the metal electrode layer, or between the n-type semiconductor material layer and the metal electrode layer; a transparent conductive layer in ohmic contact with the metal electrode layer for adjusting the uniformity of electrical injection; and an insulating passivation layer serving as a sidewall protection layer for the resonant cavity micro-light-emitting diode array device to prevent direct electrical interconnection between the p-type semiconductor material layer, the active layer, and the n-type semiconductor layer caused by subsequent evaporation of metal electrodes.

[0052] To more clearly illustrate the resonant cavity micro-light-emitting diode array device for optical interconnect applications according to embodiments of the present invention, specific examples are provided below.

[0053] Figure 2 The diagram schematically illustrates a front view of a resonant cavity micro-light-emitting diode array device for optical interconnect applications according to an embodiment of the present invention.

[0054] Figure 3The illustration schematically depicts a practical application scenario for optical interconnection, comprising a resonant cavity micro-light-emitting diode array device for optical interconnection applications according to embodiments of the present invention, and a coupling and high-speed shortwave detection array of a multi-core optical fiber in the visible light band.

[0055] like Figure 2 and Figure 3 As shown, substrate 1 can be a bonding substrate, which is formed by bonding a sapphire substrate or a silicon substrate to the original epitaxial wafer via wafer bonding.

[0056] A bonding metal layer, including metals such as Ni, Sn, and Ti, is formed on substrate 1 to bond the bonding substrate to the original epitaxial wafer.

[0057] The metal electrode layer includes a metal p electrode 3 and a metal n electrode 5.

[0058] The insulating passivation layer 4 serves as a sidewall protection layer, preventing direct electrical interconnection between the P-type doped semiconductor, the N-type doped semiconductor, and the quantum well region caused by subsequent evaporation of metal electrodes, thus achieving better electrical isolation.

[0059] The bottom distributed Bragg reflector 6 serves as the first dielectric layer, and its number of dielectric layers is greater than that of the top distributed Bragg reflector 11. It has a high reflectivity requirement, generally above 95%, and is used as a reflector in waveguides.

[0060] Indium tin oxide (ITO) 7 is mainly used for ohmic contact with metal electrodes and to ensure the uniformity of electrical injection.

[0061] The light-emitting epitaxial structure includes a P-type doped semiconductor 8, a multilayer quantum well region 9, and an N-type doped semiconductor 10.

[0062] P-type doped semiconductor 8: A pure intrinsic semiconductor doped with a small number of impurity elements with fewer valence electrons than the matrix atoms, resulting in an impurity semiconductor with a hole concentration significantly higher than the free electron concentration.

[0063] Multilayer quantum well region 9: formed by alternating growth of semiconductor thin layers with different bandgap widths, with narrow bandgap material sandwiched between wide bandgap materials, which imposes quantum confinement on the movement of charge carriers in a certain dimension, thereby producing significant quantum effects.

[0064] N-type doped semiconductor 10: A pure intrinsic semiconductor doped with a small number of impurity elements with more valence electrons than matrix atoms, resulting in an impurity semiconductor with a significantly higher concentration of free electrons than holes.

[0065] The top distributed Bragg reflector 11 serves as the second dielectric layer. The number of dielectric layers is less than that of the bottom distributed Bragg reflector 6. It has a higher reflectivity requirement, generally between 50-70%, and is used as a reflector in waveguides.

[0066] The resonant cavity micro-LED array 12 serves as the transmitter in the optical interconnect system, converting electrical signals into optical signals.

[0067] The high-speed shortwave detection array 13 serves as the receiver in the optical interconnect system, used to detect and decode the optical signal output from the transmitter and convert it into an electrical signal.

[0068] The visible light band multi-core optical fiber 14 couples the optical fiber with the micro light-emitting diode of the transmitter resonant cavity and the high-speed shortwave detection array of the receiver, so that the light propagates in the optical fiber medium, reducing the signal loss caused by propagation in free space and reducing the bit error rate during propagation.

[0069] Figure 4 A flowchart illustrating a method for fabricating a resonant cavity micro-light-emitting diode array device for optical interconnect applications according to an embodiment of the present invention is shown.

[0070] like Figure 4 As shown, the preparation method of this embodiment may include operations S410 to S420.

[0071] In operation S410, a light-emitting epitaxial structure is fabricated on a substrate, wherein material optimization is performed by etching the sidewalls of the light-emitting epitaxial structure to improve luminescence efficiency.

[0072] In operation S420, one or more combinations of plasma-enhanced chemical vapor deposition, electron beam evaporation physical vapor deposition, magnetron sputtering, and atomic layer deposition are used to prepare multilayer oxides of specific thickness and structure to form a first dielectric layer and a second dielectric layer.

[0073] The first dielectric layer, the light-emitting epitaxial structure, and the second dielectric layer constitute an optical resonant cavity structure. Photons propagate back and forth in the optical resonant cavity structure so that the wavelengths that meet the resonance conditions are retained and enhanced, and spontaneous emission light with monochromaticity and light divergence angle meeting the conditions is output.

[0074] In one example, the fabrication method of a resonant cavity micro-light-emitting diode array device for optical interconnect applications may include the following operations.

[0075] Epitaxial structure: GaN functional layers are grown on sapphire substrates using metal-organic chemical vapor deposition (MOCVD), including GaN buffer layers, n-GaN, p-GaN, and InGaN / GaN quantum wells.

[0076] Patterned ITO: An ITO layer is deposited using sputtering on the epitaxial layer. Photoresist is used as a mask, and the ITO layer is etched using an ITO etching solution to form a patterned ITO.

[0077] Mesa etching: Using photoresist as an etching mask, dry etching is performed on the epitaxial layer using methods such as inductively coupled plasma (ICP) to etch part of the epitaxial layer and form a patterned mesa.

[0078] Sidewall passivation: SiO2 and other passivation layers are deposited as sidewall insulating protective layers using methods such as plasma enhanced chemical vapor deposition (PECVD).

[0079] Metal electrode deposition: After depositing an insulating passivation layer, photolithography is performed, using photoresist as a mask for metal stripping. Subsequently, metal electrodes and the metal required for the wires are deposited, and the photoresist is removed using a blue film, a stripping agent, etc.

[0080] Metal electrode thermal annealing: This process improves the interface characteristics between metal and semiconductor through high-temperature treatment, optimizes ohmic contact characteristics, reduces the impact of parasitic resistance, and enhances device speed and energy efficiency.

[0081] Top / bottom distributed Bragg reflector: A multilayer oxide with a specific thickness and structure is prepared by electron beam evaporation (EB) to form a structure with high reflectivity at the bottom and low reflectivity at the top.

[0082] Wafer bonding: Generally, thermal compression bonding (TCB) is adopted. After the ITO, bottom DBR and back metal electrode are fabricated on the back side, bonding metal is deposited on the substrate to be transferred and the epitaxial structure. Under certain temperature and pressure, the metal atoms diffuse and come into close contact to achieve bonding, which has better conductivity, higher thermal conductivity and bonding strength.

[0083] Laser lift-off (LLO): An advanced process that uses a high-energy pulsed laser to act on the material interface to achieve precise separation and transfer. It can non-destructively peel and transfer Micro-LED chips from sapphire wafers.

[0084] Chemical mechanical polishing (CMP) combines chemical etching with mechanical abrasion to achieve nanoscale planarization of the wafer surface. This process is required after laser lift-off to flatten the surface and remove the u-GaN portion.

[0085] It should be noted that for details not covered in the preparation method examples, please refer to the semiconductor device examples; specific details will not be repeated here.

[0086] The embodiments of the present invention have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of the invention. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of the invention is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of the invention, and all such substitutions and modifications should fall within the scope of the invention.

Claims

1. A resonant cavity micro-LED array device for optical interconnect applications, characterized in that, include: Substrate; A first dielectric layer is formed on the substrate. A light-emitting epitaxial structure is formed on the first dielectric layer; The second dielectric layer is formed on the light-emitting epitaxial structure. The first dielectric layer, the light-emitting epitaxial structure, and the second dielectric layer constitute an optical resonant cavity structure. Photons propagate back and forth in the optical resonant cavity structure so that wavelengths that meet the resonance conditions are retained and enhanced, and spontaneous emission light with monochromaticity and light divergence angle meeting the conditions is output.

2. The resonant cavity micro-light emitting diode device of claim 1, wherein, Both the first dielectric layer and the second dielectric layer are periodically distributed Bragg reflective dielectric layers, and the number of periodically distributed Bragg reflective dielectric layers in the first dielectric layer is greater than the number of periodically distributed Bragg reflective dielectric layers in the second dielectric layer.

3. The resonant cavity micro-light emitting diode device of claim 2, wherein, The light-emitting epitaxial structure has the same light-emitting operating wavelength as the periodically distributed Bragg reflector layer. The reflectivity of the first dielectric layer is greater than or equal to 95%, and the reflectivity of the second dielectric layer is 50% to 70%.

4. The resonant cavity micro light-emitting diode device according to any one of claims 1 to 3, characterized in that, The materials of the first dielectric layer and the second dielectric layer include one or more combinations of silicon oxide, titanium oxide, hafnium oxide, and tantalum pentoxide.

5. The resonant cavity micro-LED device of any one of claims 1-3, wherein the first and second electrodes are formed of a transparent conductive oxide. The optical crosstalk between each micro-light-emitting unit in the resonant cavity micro-light-emitting diode array device is positively correlated with the light emission angle of the resonant cavity micro-light-emitting diode. The coupling efficiency between the optical fiber and the light-emitting unit in a resonant cavity micro-LED array device is negatively correlated with the light emission angle of the resonant cavity micro-LED. The monochromaticity of the light-emitting unit in the resonant cavity micro-LED array device is negatively correlated with the full width at half maximum (FWHM) of the resonant cavity micro-LED. The coupling quality between the optical fiber and the light-emitting unit in the resonant cavity micro-LED array device is negatively correlated with the full width at half maximum (FWHM) of the resonant cavity micro-LED. In resonant cavity micro-LED array devices, fiber loss is positively correlated with the full width at half maximum (FWHM) of the micro-LEDs.

6. The resonant cavity micro-LED array device of claim 5, wherein the first and second electrodes are formed of a transparent conductive oxide. The light-emitting unit array in the resonant cavity micro-LED array device is a linear array or a surface array; the wiring method of the resonant cavity micro-LED array device is multi-layer wiring; The diameter or length and width dimensions of the light-emitting unit are 0.5μm to 100μm.

7. The resonant cavity micro-LED array device of claim 1, wherein the first and second electrodes are formed of a transparent conductive material. The substrate includes one or more of silicon substrates, sapphire substrates, silicon carbide substrates, and gallium nitride substrates.

8. The resonant cavity micro-LED array device of claim 1, wherein, The light-emitting epitaxial structure includes an n-type semiconductor material layer, an active layer, and a p-type semiconductor material layer stacked sequentially, or a p-type semiconductor material layer, an active layer, and an n-type semiconductor material layer stacked sequentially. The active layer is made of one or more of aluminum-doped gallium nitride and indium-doped gallium nitride.

9. The resonant cavity micro-LED array device of claim 8, wherein, Also includes: A metal electrode layer is formed on the surface of the quantum well epitaxial structure away from the substrate; the material of the metal electrode layer includes one or more of aluminum, silver, nickel, gold, platinum, chromium, titanium, or copper; An insulating dielectric layer is located between the p-type semiconductor material layer and the metal electrode layer, or between the n-type semiconductor material layer and the metal electrode layer; A transparent conductive layer, in ohmic contact with the metal electrode layer, is used to adjust the uniformity of electrical injection; An insulating passivation layer serves as a sidewall protection layer for the resonant cavity micro-LED array device, preventing direct electrical interconnection between the p-type semiconductor material layer, the active layer, and the n-type semiconductor material layer caused by subsequent evaporation of metal electrodes.

10. A method for fabricating a resonant cavity micro-light-emitting diode array device for optical interconnect applications, characterized in that, include: A light-emitting epitaxial structure is fabricated on a substrate, wherein the material is optimized by etching the sidewalls of the light-emitting epitaxial structure to improve the light-emitting efficiency; A multilayer oxide with a specific thickness and structure is prepared by one or more combinations of plasma-enhanced chemical vapor deposition, electron beam evaporation physical vapor deposition, magnetron sputtering, and atomic layer deposition to form a first dielectric layer and a second dielectric layer. The first dielectric layer, the light-emitting epitaxial structure, and the second dielectric layer constitute an optical resonant cavity structure. Photons propagate back and forth in the optical resonant cavity structure so that the wavelengths that meet the resonance conditions are retained and enhanced, and spontaneous emission light with monochromaticity and light divergence angle meeting the conditions is output.

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