Anti-seismic CPO optical coupling fixing structure and preparation method

Abstract

The application discloses an anti-vibration CPO optical coupling fixing structure and a preparation method thereof. The structure comprises a silicon base material, a three-stage buffer slope positioning groove is formed in the silicon base material, and the three-stage buffer slope positioning groove comprises a guiding area, a stress release area and a locking area in sequence. A metallization layer is arranged on the inner wall of the locking area, and an optical fiber is metallurgically combined with the metallization layer through AuSn eutectic solder. MEMS cantilever stress compensators composed of U-shaped cutting gaps and silicon island cantilevers are arranged on both sides of a fiber entry point of the positioning groove on the silicon base material. The preparation method comprises silicon base positioning groove etching, metallization treatment, optical fiber eutectic bonding and MEMS cantilever processing. Through the synergistic effect of the three-stage buffer positioning groove, eutectic solder rigid fixing and the MEMS cantilever stress compensation, the coupling loss fluctuation is less than or equal to 0.2 dB under 50G high impact, typical equipment vibration frequency bands are effectively isolated, and the alignment offset problem of the optical fiber and the photonic chip coupling interface in an extreme environment is solved.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic co-packaging (CPO) technology, and relates to a shock-resistant CPO optical coupling fixing structure and its preparation method, which is suitable for packaging optical transceiver components in high vibration and high impact environments. Background Technology

[0002] Co-packaged optical fiber (CPO) technology is a core technology for overcoming the bandwidth and power consumption bottlenecks in optical communication systems for data centers, high-performance computing, and extreme environments. Its core lies in achieving high-precision optical coupling and long-term stable fixation between optical fibers and silicon photonic chips. In existing CPO and optical module packaging, the coupling and fixation of optical fibers and silicon photonic chips mostly uses ultraviolet-cured adhesives (UV adhesives). While this fixation method can meet basic usage requirements under normal conditions, it has inherent drawbacks that are difficult to overcome in extreme environments such as continuous strong vibrations and instantaneous high-gravity acceleration impacts of 50G and above. On the one hand, polymer adhesives are prone to micro-plastic creep or even cracking under long-term mechanical stress or thermal cycling, which leads to optical alignment misalignment between optical fiber and silicon photonic waveguide, causing significant fluctuations in coupling loss. On the other hand, existing packaging structures can only passively withstand external impacts and vibrations, and lack effective stress filtering and compensation mechanisms. Stress energy at a specific resonant frequency will be directly transmitted to the precision optical coupling interface, severely reducing the long-term reliability of optical transceiver components.

[0003] To address these issues, the industry has proposed several improvement solutions. For example, welding can be used instead of UV adhesive to fix and reinforce optical devices, improving the fixation strength. However, such solutions only provide localized reinforcement at the module level and lack microscale stress control design at the coupling interface. They cannot disperse the thermal and mechanical stresses at the welding points and coupling interfaces, and still struggle to cope with optical alignment misalignment issues under high-impact environments. Another example is the application of AuSn eutectic bonding technology to the high-precision mounting of lasers and photonic integrated chips, achieving high alignment accuracy. However, this technology is only an independent application of a single technology and is not integrated with the coupled and fixed structural design. It lacks a corresponding stress relief structure and cannot solve the problem of transmission of welding thermal stress and external impact stress. Furthermore, the existing compact and integrated structure design of CPO packaging only focuses on improving packaging density and coupling efficiency, without considering the application requirements of extreme mechanical environments. The shockproof solutions of traditional optical devices only adopt the module-level protection approach of "shell reinforcement + elastic buffer pad", which cannot perform targeted stress control on the core precision area of ​​the fiber-silicon photonic waveguide coupling interface, and still cannot solve the problems of stress transmission and alignment misalignment at the coupling interface. Summary of the Invention

[0004] The purpose of this invention is to provide a shock-resistant CPO optical coupling fixing structure and its fabrication method, achieving a performance index where the optical coupling loss fluctuation value is stable within ≤0.2dB under 50G instantaneous mechanical shock; by integrating a passive buffer structure and an active frequency domain stress filtering mechanism, it effectively avoids the typical equipment vibration frequency band from 10Hz to 2000Hz; at the same time, it provides a precise and reliable fabrication process route, realizing low-cost, high-yield industrial production of this structure, filling the gap in the application of CPO technology in extreme mechanical environments.

[0005] The objective of this invention is achieved through the following technical solution: A seismic-resistant CPO optical coupling fixing structure, comprising: A silicon substrate is provided with a silicon-based positioning groove adapted to the optical fiber. The silicon-based positioning groove is a three-level buffer slope positioning groove, which consists of a guiding area, a stress relief area and a locking area in sequence along the optical fiber insertion direction. A metallization layer is disposed in the silicon-based positioning groove, and the metallization layer at least covers the inner wall of the locking area; The metallization layer on the inner wall of the locking region is metallurgically bonded to the optical fiber through AuSn eutectic solder. MEMS cantilever stress compensators are provided on both sides of the optical fiber entry point of the silicon-based positioning groove on the silicon substrate. The MEMS cantilever stress compensator is composed of a U-shaped cut slit and a silicon island cantilever. The silicon island cantilever is separated from the silicon substrate to form a micro mechanical oscillator.

[0006] As a further improvement of the present invention, the guiding area is a ramp structure for guiding the insertion of the optical fiber; the stress relief area is a concave arc surface that remains in non-contact with the optical fiber for dispersing stress; and the locking area is a micro-slope structure for precisely positioning the optical fiber.

[0007] As a further improvement of the present invention, the metallization layer is a Ti / Pt / Au three-layer composite structure, consisting of a Ti adhesion layer, a Pt barrier layer, and an Au wetting layer from bottom to top.

[0008] As a further improvement of the invention, the natural frequency of the silicon island cantilever is configured to be higher than 2000Hz to avoid the typical equipment vibration frequency range of 10Hz to 2000Hz.

[0009] A method for fabricating a seismic-resistant CPO optical coupling fixing structure includes the following steps: S1. Silicon-based positioning groove etching: A three-level buffer slope positioning groove is etched on the silicon substrate, which consists of a guide area, a stress relief area, and a locking area along the fiber insertion direction. S2. Metallization treatment in silicon-based positioning groove: A metallization layer is prepared on the inner wall of at least the locking area of ​​the silicon-based positioning groove; S3. Fiber eutectic bonding: AuSn eutectic solder is placed in the groove formed by the metallization layer, and the optical fiber is inserted. The optical fiber and the silicon substrate are rigidly fixed by eutectic bonding. S4. MEMS cantilever fabrication: Using MEMS technology, U-shaped cut gaps and silicon island-type cantilever are fabricated on both sides of the optical fiber entry point of the silicon-based positioning groove to form a MEMS cantilever stress compensator.

[0010] As a further improvement of the present invention, in step S1, the guiding area is set as a 30° slope structure, the locking area is set as a 15° micro-slope structure, and the stress release area is an inwardly concave arc surface with a curvature radius R=50μm.

[0011] As a further improvement of the present invention, in step S2, the metallization layer is a Ti / Pt / Au three-layer composite structure, which is prepared by sputtering deposition process, and consists of a Ti adhesion layer, a Pt barrier layer and an Au wetting layer from bottom to top.

[0012] As a further improvement of the present invention, in step S3, the process parameters for eutectic welding are as follows: eutectic temperature controlled at 210±10℃, bonding pressure at 0.8±0.1MPa, and holding time at 30~60s.

[0013] As a further improvement of the present invention, in step S4, the U-shaped cutting slit and the silicon island cantilever are processed by femtosecond laser cutting process, and the natural frequency of the silicon island cantilever is processed to be above 2000Hz.

[0014] As a further improvement of the present invention, in step S4, the width of the U-shaped cutting slit is 20±2μm, and the cutting depth penetrates the silicon substrate; the length of the silicon island cantilever is 2.0±0.005mm, and the width is 1.0±0.005mm.

[0015] The above technical solution has the following beneficial effects: 1. Through a microscale stress control design using a three-stage buffer slope positioning groove (guiding area, stress release area, and locking area), combined with the rigid, creep-free fixation provided by AuSn eutectic solder and the active frequency domain filtering of external vibrations by a MEMS cantilever stress compensator, the alignment misalignment problem at the coupling interface between optical fiber and silicon photonic chip under high impact and strong vibration environments is effectively solved. Experimental data shows that this structure can stably control the optical coupling loss fluctuation value within ≤0.2dB under 50G instantaneous mechanical shock, significantly improving the long-term reliability of optical transceiver components in extreme environments.

[0016] 2. The concave arc surface of the stress relief zone can disperse the thermal and mechanical stress at the edge of the welding point and prevent stress peaks from propagating to the waveguide coupling area; while the MEMS cantilever stress compensator, by designing its natural frequency above 2000Hz, precisely avoids the typical equipment vibration frequency band of 10Hz to 2000Hz, thereby isolating external vibration energy outside the precision optical coupling interface and realizing full-chain control from stress generation, transmission to action.

[0017] 3. The fabrication method combines advanced processes such as deep silicon etching, selective region metallization, AuSn eutectic bonding, and femtosecond laser MEMS processing. By precisely controlling the dimensional tolerances of the positioning groove, the adhesion of the metallization layer, and the alignment accuracy of the eutectic bonding, the optical coupling accuracy between the optical fiber and the waveguide is ensured, while the metallurgical bonding strength of the welding interface is guaranteed. This eliminates the creep failure risk of traditional adhesive bonding processes and provides a reliable process guarantee for the high performance of the structure. Attached Figure Description

[0018] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0019] The structures, proportions, sizes, etc. shown in this specification are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0020] Figure 1 This is a schematic diagram of the process provided by the present invention.

[0021] Figure 2 A schematic diagram of the product structure prepared in step 1 of this invention.

[0022] Figure 3 A schematic diagram of the product structure prepared in step 2 of this invention.

[0023] Figure 4 A schematic diagram of the product structure prepared in step 3 of this invention.

[0024] Figure 5 A schematic diagram of the product structure prepared in step 4 of this invention.

[0025] Figure 6 This is a three-dimensional structural diagram provided for the present invention.

[0026] In the picture: 1. Silicon substrate; 2. SiO2 coating; 3. Silicon-based positioning groove; 31. Guiding area; 32. Locking area; 33. Stress relief area; 4. Metallization layer; 5. Optical fiber; 51. Optical fiber core; 52. Optical fiber cladding; 6. AuSn eutectic solder; 7. MEMS cantilever stress compensator; 71. U-shaped cut slit; 72. Silicon island cantilever. Detailed Implementation

[0027] In this invention, unless otherwise stated, directional terms such as "upper," "lower," "top," and "bottom" are generally used in relation to the direction shown in the accompanying drawings, or in relation to the vertical, perpendicular, or gravitational direction of the component itself; similarly, for ease of understanding and description, "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this invention.

[0028] First embodiment, such as Figure 1 As shown, a method for fabricating a seismic-resistant CPO optical coupling fixing structure includes the following steps: S1. Etching of the silicon-based positioning groove: A silicon substrate 1 is selected, which is made of high-resistivity single-crystal silicon with a resistivity ≥1000Ω・cm and a thickness of 500±10μm. After surface cleaning, a SiO2 coating 2 is coated on the surface of the silicon substrate 1 using a PECVD process. A silicon-based positioning groove 3 adapted to the optical fiber is formed on the silicon substrate 1 by exposure, development, and etching. This silicon-based positioning groove is a three-level buffer slope positioning groove, which consists of a guiding area 31, a stress relief area 33, and a locking area 32 along the optical fiber insertion direction.

[0029] The guide area, located at the entrance end of the positioning slot, has a ramp-shaped structure to provide guidance during initial fiber insertion. In a preferred embodiment, the guide area is configured with a 30° ramp structure and a ramp length of 0.5 mm. This structural design allows for certain initial assembly tolerances during fiber insertion, ensuring smooth fiber insertion into the positioning slot.

[0030] The stress relief region 33 is connected to the guiding region 31 and has a concave arc surface. This concave arc surface is treated with deep reactive ion etching during fabrication, resulting in a smooth transition without stepped burrs between it and the guiding region 31 and the locking region 32. In one specific embodiment, the stress relief region 33 is designed as a concave arc surface structure with a radius of curvature R = 50 μm, maintaining a non-contact state with the optical fiber during operation. This stress relief region 33 serves to disperse and absorb the thermal and mechanical stresses generated at the welding point edge of the coupling fixation structure, preventing stress peaks from propagating to the waveguide coupling region.

[0031] The locking region 32 is located after the stress relief region 33, i.e., at the innermost side of the positioning groove, and its structure is a micro-slope. In one specific embodiment, the locking region 32 is configured as a 15° micro-slope structure with a slope length of 1.0 mm. This angle setting is beneficial for optical calibration, ensuring that the optical fiber is accurately positioned in the locking region. The structure of the fabricated product is as follows. Figure 2 As shown.

[0032] In the fabrication of the aforementioned silicon-based positioning groove, an ICP-type deep silicon ion etching machine was used for etching. The etching rate could be controlled within the range of 1–2 μm / min, and the slope angle error was no greater than ±0.5°. The groove depth was 62.5 ± 0.5 μm, and the groove width was 125 ± 0.2 μm. After etching, the groove wall was polished to remove stepped serrations and burrs. The coaxiality deviation between the central axis of the silicon-based positioning groove and the central axis of the silicon photonic waveguide was no greater than 0.1 μm to ensure the accuracy of optical coupling.

[0033] S2. Metallization treatment inside the silicon-based positioning tank: First, a plasma cleaner is used to clean the inside of the silicon-based positioning tank 3 with O2 plasma to remove surface residues and improve the adhesion of subsequent film layers. As a preferred embodiment, the cleaning power is set to 100-150W, and the cleaning time is controlled to be 5-10 minutes.

[0034] After cleaning, a predetermined area requiring metallization within the silicon-based positioning trench 3 is pre-defined using photoresist coating. This predetermined area at least covers the inner wall of the locking region 32. In this step, the photoresist serves as a selective mask. Subsequently, a Ti / Pt / Au three-layer metallization layer 4 is fabricated in the predetermined area using a sputtering deposition system. This metallization layer 4 consists of a Ti adhesion layer, a Pt barrier layer, and an Au wetting layer, with thicknesses of 50 nm, 100 nm, and 200 nm, respectively, from bottom to top. The Ti adhesion layer adheres tightly to the inner wall of the silicon-based positioning trench, enhancing the bonding strength between the metallization layer 4 and the silicon-based positioning trench 3; the Au wetting layer forms a good wetting bond with the AuSn eutectic solder.

[0035] After sputtering deposition, the photoresist and excess metal outside the predetermined area are removed, leaving metallization layer 4 only within the designated area, providing a precise welding interface for subsequent eutectic bonding. The resulting product structure is as follows: Figure 3 As shown.

[0036] In the above-mentioned metallization layer preparation process, as a preferred embodiment, the sputtering deposition vacuum degree is controlled at ≤5×10⁻⁶. -4 Pa is used to sequentially sputter Ti, Pt, and Au using magnetron sputtering, wherein: the purity of the Au target material is not less than 99.99%; the adhesion between the metallization layer and the inner wall of the positioning groove is not less than 5 N / mm², and the uniformity deviation of the film layer does not exceed ±5nm, so as to ensure the reliability and consistency of the welding interface.

[0037] S3. Fiber Eutectic Bonding: An automatic fiber alignment system and a eutectic bonding machine are used to complete fiber eutectic bonding. Pre-placed AuSn eutectic solder is placed in the groove formed by the metallization layer 4, and then the optical fiber is inserted. In a preferred embodiment, the heating rate to the eutectic point is no more than 5℃ / s to reduce thermal stress impact; the eutectic temperature is controlled within the range of 210±10℃, the bonding pressure is 0.8±0.1MPa, and the holding time is 30~60s, allowing the AuSn eutectic solder to fully wet the Au wetting layer surface, forming a strong metallurgical bond, achieving rigid fixation of the optical fiber, and effectively preventing creep.

[0038] During the bonding process, an automatic fiber alignment system, combined with real-time optical power monitoring, ensures that the alignment accuracy between fiber 5 and locking region 32 is controlled within ±0.1μm. The initial optical coupling loss is no higher than 0.5dB to ensure the stability of optical signal transmission.

[0039] In this design, the optical fiber 5 includes an optical fiber core 51 and an optical fiber cladding 52. The outer diameter of the optical fiber cladding 52 is 125 μm, and the fitting gap between it and the slot width of the locking region 32 is 0–0.2 μm. This gap setting achieves precise positioning of the optical fiber 5 while avoiding assembly stress caused by interference fit.

[0040] The AuSn eutectic solder 6 uses Au 80 Sn 20 The eutectic solder sheet has a purity of not less than 99.9% and a thickness of 15–25 μm. This solder sheet exhibits excellent wetting compatibility with the Au wetting layer, ensuring strong metallurgical bond strength. The structure of the prepared product is as follows: Figure 4 As shown.

[0041] S4. MEMS Cantilever Fabrication: The cantilever stress compensator is fabricated using MEMS technology. Specifically, a femtosecond laser cutter and a scanning electron microscope are used to fabricate U-shaped cutting slits 71 and silicon island-type cantilever 72 on both sides of the fiber entry point of the silicon-based positioning groove 3. The two are symmetrically distributed and together constitute the MEMS cantilever stress compensator 7. This structure is used to absorb external vibration and thermal stress, ensuring the long-term stability of the optical coupling interface.

[0042] In a preferred embodiment, the pulse width of the femtosecond laser cutting machine is no greater than 500 fs, the laser power is set to 50–80 W, and the cutting speed is controlled at 5–10 mm / s. High-purity nitrogen is used for slag removal during the cutting process to ensure a clean cut surface. After cutting, the U-shaped kerf edge is neat and free of chipping, the silicon island cantilever 72 is free of microscopic cracks, and the length tolerance is controlled within ±5 μm.

[0043] The width of the U-shaped slit 71 is 20±2μm, and the cutting depth penetrates the silicon substrate 1. The length of the silicon island cantilever 72 is 2.0±0.005mm, the width is 1.0±0.005mm, and the thickness is consistent with that of the silicon substrate 1. The natural frequency of this cantilever is designed to be above 2000Hz, preferably 2200~2800Hz, to precisely avoid the typical equipment vibration frequency band of 10~2000Hz. The elastic modulus of the silicon island cantilever is 130~135GPa, which can ensure elastic recovery capability under micron-level deformation. The structure of the product prepared by it is as follows. Figure 5 As shown.

[0044] S5. Terminal Performance Test: Terminal performance tests are conducted on the products that have completed MEMS cantilever processing. First, ultrasonic cleaning is performed using anhydrous ethanol as the cleaning medium, at a frequency of 40–60 kHz, for a time of 5–8 minutes.

[0045] After cleaning, the product was placed on an impact / vibration test bench and subjected to a 50G triaxial impact. The impact test used a half-sine wave waveform, with an impact duration of 10ms, and three impacts were applied to each axis. After the test, the coupling loss was measured using an optical power meter, and the physical structure was observed using a scanning electron microscope. The acceptance criteria were that the coupling loss fluctuation was no greater than 0.2dB, the physical structure showed no loosening or cracking, and there was no obvious stress discoloration at the fiber root.

[0046] Combination Figure 5 and Figure 6 As shown, a seismic-resistant CPO optical coupling fixing structure is prepared by the above method, including: a silicon substrate 1, on which a silicon-based positioning groove 3 adapted to the optical fiber is formed, the silicon-based positioning groove is a three-level buffer slope positioning groove, which consists of a guiding area 31, a stress relief area 33 and a locking area 32 in sequence along the optical fiber insertion direction. A metallization layer 3 is provided in the silicon-based positioning groove 3. The metallization layer 3 covers at least the locking region 32 and is a Ti / Pt / Au three-layer composite structure. From bottom to top, it consists of a Ti adhesion layer, a Pt barrier layer and an Au wetting layer, with layer thicknesses of 50nm, 100nm and 200nm, respectively. The inner wall of the locking area of ​​the three-level buffer slope positioning groove 3 is covered with a metallization layer 3. The metallization layer 4 and the optical fiber 5 are metallurgically bonded by AuSn eutectic solder 6. MEMS cantilever stress compensators 7 are provided on both sides of the optical fiber entry point of the silicon substrate 1. The MEMS cantilever stress compensator 7 is composed of two symmetrical U-shaped cut slits 71 and a silicon island cantilever 72. The silicon island cantilever 72 is separated from the silicon substrate 1 to form a micro mechanical oscillator, whose natural frequency avoids the typical equipment vibration frequency band of 10-2000Hz. Example

[0047] This embodiment fabricates a shock-resistant CPO optical coupling fixing structure. The silicon substrate 1 is made of high-resistivity single-crystal silicon (resistivity ≥1000Ω・cm) with a thickness of 500μm; the optical fiber 5 is a standard single-mode optical fiber with a core diameter of 9μm and a cladding diameter of 125μm; the AuSn eutectic solder is Au 80 Sn 20 Eutectic solder sheet, 20μm thick.

[0048] The preparation was carried out according to the above method, and the key process parameters for each step are as follows: S1. Etching of silicon-based positioning groove: etching rate 1.5μm / min, guide area 30° slope angle error +0.3°, locking area 15° micro-slope angle error -0.2°, groove depth 62.5μm, groove width 125μm, coaxiality deviation between the central axis of the silicon-based positioning groove and the central axis of the silicon photonic waveguide 0.08μm; S2, Positioning groove metallization treatment: sputtering vacuum degree 3×10 -4 Pa, Ti sputtering power 90W, time 120s, Pt sputtering power 130W, time 200s, Au sputtering power 180W, time 300s, Au target purity 99.999%, metallization layer 4 adhesion 6N / mm², film uniformity deviation 3nm. S3, Fiber eutectic bonding: heating rate 4℃ / s, eutectic temperature 210℃, bonding pressure 0.8MPa, holding pressure 45s, cooling rate 2℃ / s, alignment accuracy 0.09μm, initial coupling loss 0.4dB; S4, MEMS cantilever processing: femtosecond laser power 60W, cutting speed 8mm / s, U-shaped cutting kerf 71 width 20μm, silicon island cantilever 72 length 2.0mm, width 1.0mm, natural frequency test value 2500Hz, avoiding the 10-2000Hz vibration frequency band. S5. Terminal performance test: Ultrasonic cleaning frequency 50kHz, cleaning time 6min, 50G triaxial half sine wave impact (duration 10ms), optical coupling loss fluctuation value after impact 0.15dB, no relaxation or cracking in physical structure, no stress discoloration at the root of optical fiber. Example

[0049] This embodiment fabricates a shock-resistant CPO optical coupling fixing structure. The silicon substrate is high-resistivity single-crystal silicon with a thickness of 500 μm; the optical fiber is multimode fiber with a core diameter of 50 μm and a cladding diameter of 125 μm; the AuSn eutectic solder is Au. 80 Sn 20 Eutectic solder sheet, 25μm thick.

[0050] The preparation was carried out according to the above method, and the key process parameters for each step are as follows: S1. Etching of silicon-based positioning groove: etching rate 1μm / min, guide area 30° ramp angle error +0.2°, locking area 15° micro ramp angle error +0.1°, groove depth 62.0μm, groove width 125.1μm, coaxiality deviation between the central axis of the silicon-based positioning groove and the central axis of the silicon photonic waveguide 0.07μm; S2, Positioning groove metallization treatment: sputtering vacuum degree 4×10 -4 Pa, Ti sputtering power 80W, time 130s, Pt sputtering power 120W, time 210s, Au sputtering power 150W, time 320s, Au target purity 99.99%, metallization layer adhesion 5.5N / mm², film uniformity deviation 4nm. S3, Fiber eutectic bonding: heating rate 3℃ / s, eutectic temperature 205℃, bonding pressure 0.7MPa, holding pressure 60s, cooling rate 2℃ / s, alignment accuracy 0.08μm, initial coupling loss 0.35dB; S4, MEMS cantilever processing: femtosecond laser power 50W, cutting speed 5mm / s, U-shaped cutting kerf width 19μm, silicon island cantilever length 1.998mm, width 0.999mm, natural frequency test value 2800Hz, avoiding the 10-2000Hz vibration frequency band. S5. Terminal performance test: Ultrasonic cleaning frequency 40kHz, cleaning time 8min, 50G triaxial half sine wave impact (duration 10ms), optical coupling loss fluctuation value after impact 0.12dB, no relaxation or cracking in physical structure, no stress discoloration at the root of optical fiber. Example

[0051] This embodiment fabricates a shock-resistant CPO optical coupling fixing structure. The silicon substrate is high-resistivity single-crystal silicon with a thickness of 500 μm; the optical fiber is a polarization-maintaining fiber with a core diameter of 9 μm and a cladding diameter of 125 μm; the AuSn eutectic solder is Au. 80 Sn 20 Eutectic solder sheet, 15μm thick.

[0052] The preparation was carried out according to the above method, and the key process parameters for each step are as follows: S1. Etching of silicon-based positioning groove: etching rate 2μm / min, guide area 30° slope angle error -0.3°, locking area 15° micro-slope angle error -0.1°, groove depth 63.0μm, groove width 124.9μm, coaxiality deviation between the central axis of the silicon-based positioning groove and the central axis of the silicon photonic waveguide 0.09μm; S2, Positioning groove metallization treatment: sputtering vacuum degree 2×10 -4 Pa, Ti sputtering power 100W, time 110s, Pt sputtering power 150W, time 190s, Au sputtering power 200W, time 280s, Au target purity 99.999%, metallization layer adhesion 7N / mm², film uniformity deviation 2nm. S3, Fiber eutectic bonding: heating rate 5℃ / s, eutectic temperature 215℃, bonding pressure 0.9MPa, holding pressure 30s, cooling rate 3℃ / s, alignment accuracy 0.1μm, initial coupling loss 0.45dB; S4, MEMS cantilever processing: femtosecond laser power 80W, cutting speed 10mm / s, U-shaped cutting kerf width 21μm, silicon island cantilever length 2.003mm, width 1.002mm, natural frequency test value 2200Hz, avoiding the 10-2000Hz vibration frequency band. S5. Terminal performance test: Ultrasonic cleaning frequency 60kHz, cleaning time 5min, 50G triaxial half sine wave impact (duration 10ms), optical coupling loss fluctuation value after impact 0.18dB, no relaxation or cracking in physical structure, no stress discoloration at the root of optical fiber.

[0053] The preparation results of the above three embodiments show that the preparation method of the present invention can stably realize the preparation of the shock-resistant CPO optical coupling fixing structure. The prepared structures all meet the performance index of coupling loss fluctuation ≤0.2dB under 50G high impact, and the structure has good physical integrity, which makes it feasible for industrial mass production.

[0054] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0055] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A seismic-resistant CPO optical coupling fixing structure, characterized in that, include: Silicon substrate (1), on which a silicon-based positioning groove (3) adapted to the optical fiber is provided, the silicon-based positioning groove (3) is a three-level buffer slope positioning groove, which is a guide area (31), a stress release area (33) and a locking area (32) in sequence along the optical fiber insertion direction. A metallization layer (4) is provided inside the silicon-based positioning groove (3), and the metallization layer (4) at least covers the inner wall of the locking area (32); The metallization layer (4) on the inner wall of the locking area (32) and the optical fiber (5) are metallurgically bonded together by AuSn eutectic solder (6); MEMS cantilever stress compensators (7) are provided on both sides of the optical fiber entry point of the silicon-based positioning groove (3) on the silicon substrate (1). The MEMS cantilever stress compensator (7) is composed of a U-shaped cut slit (71) and a silicon island cantilever (72). The silicon island cantilever (72) is separated from the silicon substrate (1) to form a micro mechanical oscillator.

2. The seismic-resistant CPO optical coupling fixing structure according to claim 1, characterized in that, The guiding area (31) is a ramp structure used to guide the insertion of the optical fiber; the stress relief area (33) is a concave arc surface that remains in non-contact with the optical fiber and is used to disperse stress; the locking area (32) is a micro-slope structure used to accurately position the optical fiber.

3. The seismic-resistant CPO optical coupling fixing structure according to claim 1, characterized in that, The metallization layer (4) is a Ti / Pt / Au three-layer composite structure, consisting of a Ti adhesion layer, a Pt barrier layer, and an Au wetting layer from bottom to top.

4. The seismic-resistant CPO optical coupling fixing structure according to claim 1, characterized in that, The natural frequency of the silicon island cantilever (72) is configured to be higher than 2000Hz to avoid the typical equipment vibration frequency range of 10Hz to 2000Hz.

5. A method for fabricating a seismic-resistant CPO optical coupling fixing structure, characterized in that, Includes the following steps: S1. Silicon-based positioning groove etching: A three-level buffer slope positioning groove is etched on the silicon substrate (1), which is the guide area (31), stress release area (33) and locking area (32) in sequence along the fiber insertion direction. S2, Metallization treatment in silicon-based positioning groove: A metallization layer (4) is prepared on the inner wall of at least the locking area (32) of the silicon-based positioning groove (3). S3, Fiber eutectic bonding: AuSn eutectic solder (6) is placed in the groove formed by the metallization layer (4), and fiber (5) is placed in it. The fiber (5) is rigidly fixed to the silicon substrate (1) by eutectic bonding. S4, MEMS cantilever processing: U-shaped cutting slots (71) and silicon island cantilever (72) are processed on both sides of the optical fiber entry point of the silicon-based positioning groove (3) using MEMS technology to form a MEMS cantilever stress compensator (7).

6. The preparation method according to claim 5, characterized in that, In step S1, the guide area (31) is set as a 30° slope structure, the locking area (32) is set as a 15° micro-slope structure, and the stress release area (33) is an inwardly concave arc surface with a radius of curvature R=50μm.

7. The preparation method according to claim 5, characterized in that, In step S2, the metallization layer (4) is a Ti / Pt / Au three-layer composite structure, which is prepared by sputtering deposition process. From bottom to top, it consists of a Ti adhesion layer, a Pt barrier layer and an Au wetting layer.

8. The preparation method according to claim 5, characterized in that, In step S3, the process parameters for eutectic welding are as follows: eutectic temperature is controlled at 210±10℃, bonding pressure is 0.8±0.1MPa, and holding time is 30~60s.

9. The preparation method according to claim 5, characterized in that, In step S4, the U-shaped cutting slit (71) and the silicon island cantilever (72) are processed using femtosecond laser cutting technology, and the inherent frequency of the silicon island cantilever (72) is processed to be above 2000Hz.

10. The preparation method according to claim 5, characterized in that, In step S4, the width of the U-shaped cutting slit (71) is 20±2μm, and the cutting depth penetrates the silicon substrate (1); the length of the silicon island cantilever (72) is 2.0±0.005mm, and the width is 1.0±0.005mm.

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