A high-precision low-loss high optical module preparation method

Abstract

The application discloses a high-precision low-loss high optical module preparation method and belongs to the technical field of optical communication device preparation. The method comprises the following steps: S1, selecting a suitable base material, pretreating the base material, and constructing a standardized process base; S2, relying on the standardized process base, performing pre-positioning structure forming, device pretreatment, and accurate assembly of an optical path core device, and constructing an initial optical path module; S3, performing curing and curing deformation secondary calibration on the initial optical path, and completing optical path shaping of the module; S4, after the optical path shaping, completing optical and electrical integration of the module by means of low-temperature flip-chip bonding; S5, performing impurity removal and packaging on the optical and electrical integration module, and completing packaging and forming of the overall structure of the module; and S6, performing hierarchical testing on the packaged module, and completing optical module preparation. By adopting the method, high-yield, high-reliability, and low-cost mass production of high-speed optical modules are realized.

Description

Technical Field

[0001] This invention belongs to the field of optical communication device fabrication technology, and in particular relates to a method for fabricating a high-precision, low-loss, and high-performance optical module. Background Technology

[0002] Currently, the mainstream manufacturing processes for high-speed optical modules include three categories: TO coaxial packaging, COB on-board chip packaging, and silicon photonics hybrid integrated packaging. These are the core technologies for the mass production of 400G and above high-speed optical modules. As optical communication iterates towards ultra-high speed, high density, low latency, and long lifespan, existing manufacturing processes have inherent structural defects, becoming the core bottleneck restricting the large-scale, high-yield, and high-reliability mass production of 1.6T and above ultra-high-speed optical modules. Problems include low precision and poor yield in optical coupling processes, insufficient temperature drift stability, numerous defects in packaging bonding and adhesion, and insufficient hermeticity and reliability. Summary of the Invention

[0003] The purpose of this invention is to provide a high-precision, low-loss optical module manufacturing method. By optimizing the entire process of optical path coupling, heat dissipation structure, electrical interconnection, packaging and curing, and testing and repair, the core problems of low precision and fault tolerance, thermal power consumption bottleneck, poor signal integrity, long-term aging failure and low mass production yield of ultra-high-speed optical modules are solved, thus achieving high yield, high reliability and low cost mass production of high-speed optical modules.

[0004] To achieve the above objectives, the present invention provides a method for fabricating a high-precision, low-loss optical module, comprising the following steps: S1. Select a suitable substrate and pre-treat it to construct a standardized process substrate; S2. Based on standardized process foundation, pre-positioning structure forming, device pre-processing and precise assembly of core optical path components are carried out to construct the initial optical path module; S3. Perform curing and secondary calibration of the initial optical path and curing deformation to complete the optical path shaping of the module; S4. After the optical path is finalized, the optical and electronic integration of the module is completed by low-temperature flip bonding. S5. Remove impurities and encapsulate the integrated optical and electronic module to complete the overall encapsulation and molding of the module structure. S6. Perform graded testing on the packaged modules to complete the optical module fabrication.

[0005] Preferably, the process of S1 is as follows: S11. Select high thermal conductivity aluminum nitride ceramic with a thickness of 0.7-0.9mm as the substrate, and perform initial flatness screening and dust removal on the substrate to remove defective substrates that are warped, damaged, or have excessive surface impurities. S12. After screening, the substrate is obtained. The independent functional areas are precisely divided on the surface of the substrate by nanosecond laser high-precision etching process, including the low temperature area of ​​optical devices, the high temperature area of ​​electrical chips and the isolation area of ​​TEC cooling devices. S13. At the boundaries of each functional area, the etching depth is 45-55. Width 80-100 The heat insulation groove is filled with an organosilicon heat insulation colloid with an expansion coefficient ≤20ppm / ℃ using a vacuum filling process. S14. Using a dry etching process, an integral molding depth of 90-110 is formed on the back side of the substrate. The spacing is 200. The array-type microfluidic heat dissipation channel; and the inner wall of the channel is treated with a hydrophilic and anti-oxidation coating, and a standardized air-cooling and micro-liquid-cooling dual-mode heat dissipation interface is reserved; S15. Calculate the maximum temperature drift and ensure that the error between the temperature drift of the arrayed microfluidic heat dissipation channel and the maximum temperature drift is within the allowable range. S16. Perform plasma cleaning and high-temperature stress-relief baking sequentially to eliminate internal stress and surface micro-impurities in the substrate; finally, perform flatness calibration to ensure the overall flatness of the substrate. This yields a standardized process substrate.

[0006] Preferably, the maximum temperature drift is calculated in S15. The process is as follows: ; in Indicates the power consumption of a single-area chip. This indicates the overall thermal conductivity of the substrate. This indicates the effective heat dissipation area of ​​the microchannel.

[0007] Preferably, the process of S2 is as follows: S21. In the low-temperature assembly area of ​​the standardized process substrate, an array of positioning grooves and cross-shaped alignment reference scales are integrated using nanoimprint lithography. At the same time, a micro-arc alignment boss is integrally formed on the end face of the fiber array using precision injection molding, so that the size of the boss is perfectly matched with the positioning groove of the substrate. S22. Take the core optical components to be assembled, and perform ultra-precision polishing on the optical end face of the components to remove burrs and micro protrusions; then carry out full-area dust-free degreasing cleaning to remove oil, dust and oxidation impurities from the surface of the components. S23. Pre-set a constant temperature and humidity vacuum dust-free working environment. In the working environment, place the processed optical path core components in sequence on the low temperature zone of the substrate optical device. Through the mechanical interlocking structure of the substrate positioning groove and the fiber array protrusion, complete the initial positioning and fixation, and realize the initial coaxial positioning of the device. S24. A high-precision industrial machine vision system performs full-area scanning imaging of the assembly structure. Combined with image comparison algorithms and coordinate deviation compensation algorithms, it acquires real-time three-dimensional coordinate data of the laser emitting surface center, the microlens central axis, and the fiber core axis. The coaxiality of these three components is dynamically calibrated to achieve passive pre-alignment, strictly controlling the three-dimensional optical path alignment offset to ≤0.1. Coaxiality error ≤ 0.05 This enables high-precision automated assembly without active debugging or human intervention. S25. After alignment, a second visual inspection is performed to check for defects including device misalignment, false clamps, and abnormal gaps. After confirming that all optical path alignment parameters meet the standards, the finalization is completed, resulting in a high-precision and stable optical path structure, i.e., the initial optical path module.

[0008] Preferably, the three-dimensional optical path alignment offset mentioned in S24 The calculation process is as follows: ; in These represent the alignment deviations of the X, Y, and Z axes, respectively.

[0009] Preferably, the process of S3 is as follows: S31. Using optical UV-curable adhesive and a fully automated precision dispensing device, precise micro-dispensing is performed on the bonding surfaces of optical lenses, fiber arrays, and substrate alignment interfaces, accurately controlling the adhesive layer thickness to 5-8 mm. ; S32. After dispensing, let stand for 2 seconds to defoam. Use 365nm fixed-point UV curing process, set laser stable power and single-point precise irradiation time to achieve instantaneous curing of the optical path interface, and measure the interface temperature in real time during the curing process to strictly control the maximum curing temperature to not exceed 80℃. S33. After laser curing is completed, the machine vision calibration system is activated to scan the optical path coaxiality and alignment offset of the entire area, detect the optical path deviation caused by colloid curing shrinkage and small stress deformation in real time, and complete the secondary fine-tuning alignment calibration through coordinate compensation algorithm to correct curing error. S34. After the secondary calibration is completed, place the module in a constant temperature and dust-free environment at 25℃ for 5 minutes to allow the optical colloid to be completely cured and the interface curing stress to be fully released, thus completing the permanent curing of the optical path system.

[0010] Preferably, the process of S4 is as follows: S41. Electroplating process is used to prepare a chip with a diameter of 25-30 mm on the surface of the optical chip pad and the substrate pre-set electrical chip pad. Uniform micro-bumps in high-purity copper; S42. The chip bonding and assembly is completed using a low-temperature hot-press flip-chip bonding process, which precisely controls the bonding process parameters, including bonding temperature, bonding pressure and holding time. S43. After bonding is completed, conduct conductivity testing and solder joint appearance screening, check for defects that occur during welding one by one, and remove unqualified semi-finished products. S44. An integrated vertical electromagnetic shielding isolation wall is prepared in the signal arrangement area of ​​the high-temperature region of the substrate electronic chip using a ceramic precision sintering process. S45. Through impedance tuning technology, the spacing between high-speed signal lines and the equivalent dielectric thickness are precisely calibrated to strictly lock the impedance of the entire high-speed signal link at 50Ω. Industry standard values ​​are used, and impedance errors are strictly controlled to not exceed the threshold, so as to achieve precise impedance matching of ultra-high speed signals and complete the optical and electrical integration of the module.

[0011] Preferably, the impedance of the entire high-speed signal link mentioned in S45 Calculated using the following formula: ; in Indicates the equivalent dielectric constant of the substrate. Indicates the thickness of the medium. Indicates the trace width. This indicates the thickness of the copper bump trace.

[0012] Preferably, the process of S5 is as follows: S51. The integrated optical and electronic module is placed in a vacuum cleaning chamber for plasma vacuum cleaning to remove micron-level dust, organic oil and surface oxide film adhering to the substrate, optical devices and electronic chips. S52. After plasma vacuum cleaning is completed, perform low-temperature anhydrous ethanol ultrasonic fine cleaning for a period of time, setting the ultrasonic frequency and cleaning temperature to accurately remove flux residue and micro-particle attachments from solder joints. S53. After cleaning, transfer to a vacuum drying equipment and dry in a constant temperature and vacuum environment for 30 minutes to remove moisture from the surface and micro-gaps of the device. S54. The cavity is encapsulated using a temperature-controlled metal-ceramic seamless hermetic welding process. Before welding and sealing, the cavity is subjected to multiple gas replacements and filled with dry nitrogen to control the water vapor and oxygen content inside the cavity. After welding, a gradient temperature control stress relief process is adopted, which involves heating the material at a rate of 5℃ / min to 60℃, maintaining the temperature for 30 minutes, and then cooling it down to room temperature at a natural and uniform rate to offset the interfacial stress caused by the difference in thermal expansion coefficients of different materials.

[0013] Preferably, the process of S6 is as follows: S61. Establish a testing system to sequentially complete wafer-level pre-testing, in-package testing, and finished product system-level testing, and intercept defective products in stages; S62. For products with non-structural failures, a localized precision laser degumming, point cleaning, and secondary nano-level alignment + laser curing process is used to achieve non-destructive repair. S63. Randomly sample modules that have passed inspection and completed repairs, and conduct standard high and low temperature cycle aging tests and damp heat aging tests for a certain period of time. S64. After the aging test is completed, the module's photoelectric parameters, airtightness, and signal integrity are fully re-inspected. If all indicators meet the standards, it is judged to be a qualified product, and the optical module manufacturing is completed.

[0014] Therefore, the high-precision, low-loss, and high-performance optical module fabrication method described above has the following advantages: 1. By using three-stage segmented testing to intercept defective products in advance, the rework process can reduce material scrap and solve the pain points of low yield and high loss in traditional processes; 2. By using a partitioned heat insulation + microchannel heat dissipation architecture, heat dissipation efficiency is improved, and thermal crosstalk between multiple devices is basically eliminated. The device operating temperature is stable under high temperature conditions, and wavelength drift and signal jitter problems are alleviated. 3. The process is highly automated, with good batch consistency, while also taking into account mass production capability and maintainability.

[0015] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0016] Figure 1 This is an overall flowchart of a high-precision, low-loss optical module fabrication method according to the present invention; Figure 2 This is a flowchart illustrating the construction of a standardized process substrate in a high-precision, low-loss, high-performance optical module fabrication method of the present invention. Figure 3 This is a flowchart illustrating the construction of the initial optical path module in a high-precision, low-loss, high-performance optical module fabrication method of the present invention. Figure 4 This is a flowchart of the optical path shaping process in a high-precision, low-loss optical module fabrication method of the present invention; Figure 5 This is a flowchart illustrating the optical-electrical integration process in a high-precision, low-loss, high-efficiency optical module fabrication method of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Specific model specifications need to be selected and determined according to the actual specifications of the device, etc. The specific selection calculation method adopts existing technology in the art, and therefore will not be described in detail.

[0018] Example 1; like Figures 1-5 As shown, this invention provides a method for fabricating a high-precision, low-loss optical module, comprising the following steps: S1. Select a suitable substrate and pre-treat it to construct a standardized process substrate; S11. Select high thermal conductivity aluminum nitride ceramic with a thickness of 0.7-0.9mm as the substrate, and perform initial flatness screening and dust removal on the substrate to remove defective substrates that are warped, damaged, or have excessive surface impurities. S12. After screening, the substrate is obtained. The independent functional areas are precisely divided on the surface of the substrate by nanosecond laser high-precision etching process, including the low temperature area of ​​optical devices, the high temperature area of ​​electrical chips and the isolation area of ​​TEC cooling devices. S13. At the boundaries of each functional area, the etching depth is 45-55. Width 80-100 The heat insulation groove is filled with an organosilicon heat insulation colloid with an expansion coefficient ≤20ppm / ℃ using a vacuum filling process. S14. Using a dry etching process, an integral molding depth of 90-110 is formed on the back side of the substrate. The spacing is 200. The array-type microfluidic heat dissipation channel; and the inner wall of the channel is treated with a hydrophilic and anti-oxidation coating, and a standardized air-cooling and micro-liquid-cooling dual-mode heat dissipation interface is reserved; S15. Calculate the maximum temperature drift and ensure that the error between the temperature drift of the arrayed microfluidic heat dissipation channel and the maximum temperature drift is within the allowable range. Calculate the maximum temperature drift The process is as follows: ; in Indicates the power consumption of a single-area chip. This indicates the overall thermal conductivity of the substrate. This indicates the effective heat dissipation area of ​​the microchannel.

[0019] S16. Perform plasma cleaning and high-temperature stress-relief baking sequentially to eliminate internal stress and surface micro-impurities in the substrate; finally, perform flatness calibration to ensure the overall flatness of the substrate. This yields a standardized process substrate.

[0020] S2. Based on standardized process foundation, pre-positioning structure forming, device pre-processing and precise assembly of core optical path components are carried out to construct the initial optical path module; Based on the high-precision flattened and zoned heat-insulating aluminum nitride ceramic substrate completed by S1 pretreatment, the pre-positioning structure of the core optical components is formed, the device pretreatment and nanoscale passive precision assembly are completed, and a high-precision reference optical path is constructed, providing a precise structural foundation for the subsequent optical path curing and shaping. The entire process is progressive and the parameters are controllable.

[0021] S21. In the low-temperature assembly area of ​​the standardized process substrate, an array of positioning grooves and cross-shaped alignment reference scales are integrally fabricated using nanoimprint lithography. The depth of the positioning grooves is controlled at 10-15μm, the processing accuracy is ±0.5μm, and the width of the reference scale lines is 2μm. The structure is wear-resistant and highly recognizable, serving as a precise mechanical reference for subsequent optical path assembly. At the same time, a micro-arc alignment boss is integrally formed on the end face of the fiber array using precision injection molding. The size of the boss is perfectly matched with the positioning groove of the substrate, forming a detachable mechanical interlocking pre-positioning structure, enabling rapid positioning and assembly of optical path devices. S22. Take the core optical components such as lasers, microlenses, and fiber arrays to be assembled, and perform ultra-precision polishing on the optical end faces of the components to remove burrs and micro protrusions; then carry out full-area dust-free degreasing cleaning to remove oil, dust and oxidation impurities from the surface of the components. S23. A vacuum dust-free working environment with a preset constant temperature of 25℃ and constant humidity of 45% is used to avoid micro-deformation of devices and dust pollution caused by temperature and humidity fluctuations. In the working environment, the processed optical core devices are placed in the low temperature zone of the substrate optical device in sequence. The initial positioning and fixing are completed through the mechanical interlocking structure of the substrate positioning groove and the fiber array protrusion, and the initial coaxial positioning of the device is achieved without the need for manual six-axis debugging intervention. S24. A high-precision industrial machine vision system performs full-area scanning imaging of the assembly structure. Combined with image comparison algorithms and coordinate deviation compensation algorithms, it acquires real-time three-dimensional coordinate data of the laser emitting surface center, the microlens central axis, and the fiber core axis. The coaxiality of these three components is dynamically calibrated to achieve passive pre-alignment, strictly controlling the three-dimensional optical path alignment offset to ≤0.1. Coaxiality error ≤ 0.05 This enables high-precision automated assembly without active debugging or human intervention. 3D optical path alignment offset The calculation process is as follows: ; in These represent the alignment deviations of the X, Y, and Z axes, respectively.

[0022] S25. After alignment, a second visual inspection is performed to check for defects including device misalignment, false clamps, and abnormal gaps. After confirming that all optical path alignment parameters meet the standards, the finalization is completed, resulting in a high-precision and stable optical path structure, i.e., the initial optical path module.

[0023] S3. Perform curing and secondary calibration of the initial optical path and curing deformation to complete the optical path shaping of the module; The optical path system after high-precision alignment is cured and shaped instantly without thermal shock and with low stress, correcting the micro-deformation error of curing. This completely solves the defects of traditional bonding process, such as long-term creep, optical path misalignment, and temperature drift failure, and provides a dimensionally stable and loss-constant optical path body for subsequent electrical integration.

[0024] S31. Using optical UV-curable adhesive and a fully automated precision dispensing device, precise micro-dispensing is performed on the bonding surfaces of optical lenses, fiber arrays, and substrate alignment interfaces, accurately controlling the adhesive layer thickness to 5-8 mm. To ensure uniform and full coverage of the adhesive layer, strictly avoid process defects such as excess adhesive, insufficient adhesive, air bubbles, and uneven adhesive layer thickness, and reduce curing deformation and optical loss from the source; We use a special optical UV curing adhesive with low creep, low thermal expansion, high light transmittance and aging resistance. After curing, the coefficient of thermal expansion is ≤15ppm / ℃, which is suitable for optical modules to operate in a full temperature range of -40℃ to 85℃. S32. After dispensing, let stand for 2 seconds to defoam. Use 365nm fixed-point UV curing process, set laser stable power and single-point precise irradiation time to achieve instantaneous curing of the optical path interface, and measure the interface temperature in real time during the curing process to strictly control the maximum curing temperature to not exceed 80℃. S33. After laser curing is completed, the machine vision calibration system is activated to scan the optical path coaxiality and alignment offset of the entire domain. The optical path deviation caused by colloid curing shrinkage and small stress deformation is detected in real time. The coordinate compensation algorithm is used to complete the secondary fine-tuning alignment calibration, correct the curing error, and avoid high-temperature thermal shock damage to the laser photosensitive layer, thin film waveguide and other precision optical structures, so as to achieve low-temperature non-damaging curing and shaping. S34. After the secondary calibration is completed, the module is placed in a constant temperature and dust-free environment at 25℃ for 5 minutes to allow the optical colloid to be completely cured and the interface curing stress to be fully released, thus completing the permanent shaping of the optical path system and ensuring the stability of the optical path structure and the absence of optical power drift under all temperature conditions, providing qualified semi-finished products for the electrical integration process in step four.

[0025] S4. After the optical path is finalized, the optical and electronic integration of the module is completed by low-temperature flip bonding. Based on the finalized module structure, high-speed electrical integration of optical chips, electrical chips and aluminum nitride ceramic substrate is completed. Through low parasitic flip bonding and multi-channel electromagnetic isolation design, the defects of traditional gold wire bonding, such as large parasitic parameters, strong electromagnetic crosstalk and poor signal integrity, are solved, and it is suitable for 1.6T / 3.2T ultra-high-speed PAM4 signal transmission.

[0026] S41. Electroplating process is used to prepare a chip with a diameter of 25-30 mm on the surface of the optical chip pad and the substrate pre-set electrical chip pad. The high-purity copper uniform micro-bumps are strictly controlled to ensure consistent bump height, no oxidation, no misalignment, and no burrs, thus constructing a low-impedance, short-path electrical connection substrate to replace the traditional long-wire gold wire bonding structure. S42. The chip bonding and assembly are completed using a low-temperature hot-press flip-chip bonding process, with precise control of bonding process parameters, including bonding temperature of 120℃, bonding pressure of 35-40g, and holding time of 8s, to achieve electrical interconnection with no thermal damage and low residual stress. S43. After bonding is completed, conduct continuity testing and solder joint appearance screening, check for defects in the welding process one by one, and remove unqualified semi-finished products to prevent defective products from flowing into subsequent processes and ensure the reliability of electrical connection. S44. An integrated vertical electromagnetic shielding isolation wall is prepared in the signal arrangement area of ​​the high-temperature region of the substrate electronic chip using a ceramic precision sintering process. The isolation wall is 0.3mm high and 0.1mm thick, achieving complete physical isolation and electromagnetic shielding isolation between adjacent high-speed signal channels, eliminating crosstalk and electromagnetic interference between multiple channels. S45. Through impedance tuning technology, the spacing between high-speed signal lines and the equivalent dielectric thickness are precisely calibrated to strictly lock the impedance of the entire high-speed signal link at 50Ω. Industry standard values ​​are used, and impedance errors are strictly controlled to not exceed the threshold, so as to achieve precise impedance matching of ultra-high speed signals and complete the optical and electrical integration of the module.

[0027] Impedance of the entire high-speed signal link Calculated using the following formula: ; in Indicates the equivalent dielectric constant of the substrate. Indicates the thickness of the medium. Indicates the trace width. This indicates the thickness of the copper bump trace.

[0028] S5. Remove impurities and encapsulate the integrated optical and electronic module to complete the overall encapsulation and molding of the module structure. By employing segmented precision cleaning, high-purity nitrogen gas sealing, and interface stress relief treatment, the reliability defects of traditional packaging, such as residual impurities, moisture intrusion, stress concentration, and poor airtightness, are completely resolved, thus completing the main packaging of the optical module.

[0029] S51. The integrated optical and electronic module is placed in a vacuum cleaning chamber for plasma vacuum cleaning to remove micron-level dust, organic oil and surface oxide film adhering to the substrate, optical devices and electronic chips. S52. After plasma vacuum cleaning is completed, perform low-temperature anhydrous ethanol ultrasonic fine cleaning for a period of time, setting the ultrasonic frequency and cleaning temperature to accurately remove flux residue and micro-particle attachments from solder joints. S53. After cleaning, transfer to a vacuum drying equipment and dry in a constant temperature and vacuum environment for 30 minutes to remove moisture from the surface and micro-gaps of the device. S54. The cavity is encapsulated using a temperature-controlled metal-ceramic seamless hermetic welding process. Before welding and sealing, the cavity is subjected to multiple gas replacements and filled with dry nitrogen to control the water vapor and oxygen content inside the cavity. After welding, a gradient temperature control stress relief process is adopted, which involves heating the material at a rate of 5℃ / min to 60℃, maintaining the temperature for 30 minutes, and then cooling it down to room temperature at a natural and uniform rate to offset the interfacial stress caused by the difference in thermal expansion coefficients of different materials.

[0030] S6. Perform graded testing on the packaged modules to complete the optical module fabrication.

[0031] S61. Establish a testing system to sequentially complete wafer-level pre-testing, in-package testing, and finished product system-level testing, and intercept defective products in stages; S62. For products with non-structural failures, a localized precision laser degumming, point cleaning, and secondary nano-level alignment + laser curing process is used to achieve non-destructive repair. S63. Randomly sample modules that have passed inspection and completed repairs, and conduct standard high and low temperature cycle aging tests and damp heat aging tests for a certain period of time. S64. After the aging test is completed, the module's photoelectric parameters, airtightness, and signal integrity are fully re-inspected. If all indicators meet the standards, it is judged to be a qualified product, and the optical module manufacturing is completed.

[0032] Example 2; Large-scale fabrication of 800G high-speed optical modules; Substrate fabrication: A 0.8mm thick aluminum nitride ceramic substrate was selected. The optical device area, electrical chip area and cooling isolation area were divided by laser etching. A 50μm heat insulation groove was prepared between the areas and filled with organosilicon heat insulation colloid. A 100μm microfluidic heat dissipation channel was etched on the bottom of the substrate, and a liquid cooling interface was reserved.

[0033] Pre-positioning structure fabrication: A 2μm precision positioning groove is fabricated in the optical device assembly area of ​​the substrate using nanoimprinting technology, and a micro alignment boss is injection molded on the end face of the fiber array to achieve precise mechanical interlocking.

[0034] Optical path coupling curing: Place the laser, microlens, and fiber array, and perform passive pre-alignment by machine vision scanning calibration, with the offset controlled within 0.1μm; apply UV low creep optical adhesive, and cure by irradiating the spot with a 365nm UV laser for 4s at a curing temperature of 75℃, followed by secondary calibration and fine-tuning after curing.

[0035] Electrical interconnection and shielding: The optical chip and the substrate are bonded using a copper pillar micro-bump flip-chip process with a bonding pitch of 50μm; ceramic electromagnetic isolation walls are fabricated in the multi-channel signal area, and the line impedance is precisely calibrated to the standard value of 50Ω.

[0036] Precision packaging and purification: plasma vacuum cleaning for 10 minutes to remove surface micro dust and organic residues; low-temperature ultrasonic cleaning with anhydrous ethanol for 5 minutes; vacuum drying at 120℃ for 30 minutes; metal-ceramic hermetically sealed packaging, the cavity is filled with high-purity nitrogen, and after sealing, interface stress relief treatment is performed.

[0037] Graded testing and aging: Wafer-level pre-testing, packaging loss testing, finished product system-level bit error and temperature drift testing are completed, and products with slight optical path misalignment are repaired by laser debonding; finally, 2000 hours of high and low temperature cycle aging test is carried out to screen qualified products.

[0038] Therefore, the present invention employs a high-precision, low-loss, and high-efficiency optical module fabrication method, which has the following advantages: 1. By using three-stage segmented testing to intercept defective products in advance, the rework process can reduce material scrap and solve the pain points of low yield and high loss in traditional processes; 2. By using a partitioned heat insulation + microchannel heat dissipation architecture, heat dissipation efficiency is improved, and thermal crosstalk between multiple devices is basically eliminated. The device operating temperature is stable under high temperature conditions, and wavelength drift and signal jitter problems are alleviated. 3. The process is highly automated, with good batch consistency, while also taking into account mass production capability and maintainability.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for fabricating a high-precision, low-loss optical module, characterized in that, Includes the following steps: S1. Select a suitable substrate and pre-treat it to construct a standardized process substrate; S2. Based on standardized process foundation, pre-positioning structure forming, device pre-processing and precise assembly of core optical path components are carried out to construct the initial optical path module; S3. Perform curing and secondary calibration of the initial optical path and curing deformation to complete the optical path shaping of the module; S4. After the optical path is finalized, the optical and electronic integration of the module is completed by low-temperature flip bonding. S5. Remove impurities and encapsulate the integrated optical and electronic module to complete the overall encapsulation and molding of the module structure. S6. Perform graded testing on the packaged modules to complete the optical module fabrication.

2. The method for fabricating a high-precision, low-loss optical module according to claim 1, characterized in that, The process of S1 is as follows: S11. Select high thermal conductivity aluminum nitride ceramic with a thickness of 0.7-0.9mm as the substrate, and perform initial flatness screening and dust removal on the substrate to remove defective substrates that are warped, damaged, or have excessive surface impurities. S12. After screening, the substrate is obtained. The independent functional areas are precisely divided on the surface of the substrate by nanosecond laser high-precision etching process, including the low temperature area of ​​optical devices, the high temperature area of ​​electrical chips and the isolation area of ​​TEC cooling devices. S13. At the boundaries of each functional area, the etching depth is 45-55. Width 80-100 The heat insulation groove is filled with an organosilicon heat insulation colloid with an expansion coefficient ≤20ppm / ℃ using a vacuum filling process. S14. Using a dry etching process, an integral molding depth of 90-110 is formed on the back side of the substrate. The spacing is 200. The array-type microfluidic heat dissipation channel; and the inner wall of the channel is treated with a hydrophilic and anti-oxidation coating, and a standardized air-cooling and micro-liquid-cooling dual-mode heat dissipation interface is reserved; S15. Calculate the maximum temperature drift and ensure that the error between the temperature drift of the arrayed microfluidic heat dissipation channel and the maximum temperature drift is within the allowable range. S16. Perform plasma cleaning and high-temperature stress-relief baking sequentially to eliminate internal stress and surface micro-impurities in the substrate; finally, perform flatness calibration to ensure the overall flatness of the substrate. This yields a standardized process substrate.

3. The method for fabricating a high-precision, low-loss optical module according to claim 2, characterized in that, Calculate the maximum temperature drift in S15 The process is as follows: ； in Indicates the power consumption of a single-area chip. This indicates the overall thermal conductivity of the substrate. This indicates the effective heat dissipation area of ​​the microchannel.

4. The method for fabricating a high-precision, low-loss optical module according to claim 3, characterized in that, The process of S2 is as follows: S21. In the low-temperature assembly area of ​​the standardized process substrate, an array of positioning grooves and cross-shaped alignment reference scales are integrated using nanoimprint lithography. At the same time, a micro-arc alignment boss is integrally formed on the end face of the fiber array using precision injection molding, so that the size of the boss is perfectly matched with the positioning groove of the substrate. S22. Take the core optical components to be assembled, and perform ultra-precision polishing on the optical end face of the components to remove burrs and micro protrusions; then carry out full-area dust-free degreasing cleaning to remove oil, dust and oxidation impurities from the surface of the components. S23. Pre-set a constant temperature and humidity vacuum dust-free working environment. In the working environment, place the processed optical path core components in sequence on the low temperature zone of the substrate optical device. Through the mechanical interlocking structure of the substrate positioning groove and the fiber array protrusion, complete the initial positioning and fixation, and realize the initial coaxial positioning of the device. S24. A high-precision industrial machine vision system performs full-area scanning imaging of the assembly structure. Combined with image comparison algorithms and coordinate deviation compensation algorithms, it acquires real-time three-dimensional coordinate data of the laser emitting surface center, the microlens central axis, and the fiber core axis. The coaxiality of these three components is dynamically calibrated to achieve passive pre-alignment, strictly controlling the three-dimensional optical path alignment offset to ≤0.

1. Coaxiality error ≤ 0.05 This enables high-precision automated assembly without active debugging or human intervention. S25. After alignment, a second visual inspection is performed to check for defects including device misalignment, false clamps, and abnormal gaps. After confirming that all optical path alignment parameters meet the standards, the finalization is completed, resulting in a high-precision and stable optical path structure, i.e., the initial optical path module.

5. The method for fabricating a high-precision, low-loss optical module according to claim 4, characterized in that, The three-dimensional optical path alignment offset mentioned in S24 The calculation process is as follows: ； in These represent the alignment deviations of the X, Y, and Z axes, respectively.

6. The method for fabricating a high-precision, low-loss optical module according to claim 5, characterized in that, The process of S3 is as follows: S31. Using optical UV-curable adhesive and a fully automated precision dispensing device, precise micro-dispensing is performed on the bonding surfaces of optical lenses, fiber arrays, and substrate alignment interfaces, accurately controlling the adhesive layer thickness to 5-8 mm. ; S32. After dispensing, let stand for 2 seconds to defoam. Use 365nm fixed-point UV curing process, set laser stable power and single-point precise irradiation time to achieve instantaneous curing of the optical path interface, and measure the interface temperature in real time during the curing process to strictly control the maximum curing temperature to not exceed 80℃. S33. After laser curing is completed, the machine vision calibration system is activated to scan the optical path coaxiality and alignment offset of the entire area, detect the optical path deviation caused by colloid curing shrinkage and small stress deformation in real time, and complete the secondary fine-tuning alignment calibration through coordinate compensation algorithm to correct curing error. S34. After the secondary calibration is completed, place the module in a constant temperature and dust-free environment at 25℃ for 5 minutes to allow the optical colloid to be completely cured and the interface curing stress to be fully released, thus completing the permanent curing of the optical path system.

7. The method for fabricating a high-precision, low-loss optical module according to claim 6, characterized in that, The process of S4 is as follows: S41. Electroplating process is used to prepare a chip with a diameter of 25-30 mm on the surface of the optical chip pad and the substrate pre-set electrical chip pad. Uniform micro-bumps in high-purity copper; S42. The chip bonding and assembly is completed using a low-temperature hot-press flip-chip bonding process, which precisely controls the bonding process parameters, including bonding temperature, bonding pressure and holding time. S43. After bonding is completed, conduct conductivity testing and solder joint appearance screening, check for defects that occur during welding one by one, and remove unqualified semi-finished products. S44. An integrated vertical electromagnetic shielding isolation wall is prepared in the signal arrangement area of ​​the high-temperature region of the substrate electronic chip using a ceramic precision sintering process. S45. Through impedance tuning technology, the spacing between high-speed signal lines and the equivalent dielectric thickness are precisely calibrated to strictly lock the impedance of the entire high-speed signal link at 50Ω. Industry standard values ​​are used, and impedance errors are strictly controlled to not exceed the threshold, so as to achieve precise impedance matching of ultra-high speed signals and complete the optical and electrical integration of the module.

8. The method for fabricating a high-precision, low-loss optical module according to claim 7, characterized in that, The impedance of the entire high-speed signal link mentioned in S45 Calculated using the following formula: ； in Indicates the equivalent dielectric constant of the substrate. Indicates the thickness of the medium. Indicates the trace width. This indicates the thickness of the copper bump trace.

9. The method for fabricating a high-precision, low-loss optical module according to claim 8, characterized in that, The process of S5 is as follows: S51. The integrated optical and electronic module is placed in a vacuum cleaning chamber for plasma vacuum cleaning to remove micron-level dust, organic oil and surface oxide film adhering to the substrate, optical devices and electronic chips. S52. After plasma vacuum cleaning is completed, perform low-temperature anhydrous ethanol ultrasonic fine cleaning for a period of time, setting the ultrasonic frequency and cleaning temperature to accurately remove flux residue and micro-particle attachments from solder joints. S53. After cleaning, transfer to a vacuum drying equipment and dry in a constant temperature and vacuum environment for 30 minutes to remove moisture from the surface and micro-gaps of the device. S54. The cavity is encapsulated using a temperature-controlled metal-ceramic seamless hermetic welding process. Before welding and sealing, the cavity is subjected to multiple gas replacements and filled with dry nitrogen to control the water vapor and oxygen content inside the cavity. After welding, a gradient temperature control stress relief process is adopted, which involves heating the material at a rate of 5℃ / min to 60℃, maintaining the temperature for 30 minutes, and then cooling it down to room temperature at a natural and uniform rate to offset the interfacial stress caused by the difference in thermal expansion coefficients of different materials.

10. The method for fabricating a high-precision, low-loss optical module according to claim 9, characterized in that, The process of S6 is as follows: S61. Establish a testing system to sequentially complete wafer-level pre-testing, in-package testing, and finished product system-level testing, and intercept defective products in stages; S62. For products with non-structural failures, a localized precision laser degumming, point cleaning, and secondary nano-level alignment + laser curing process is used to achieve non-destructive repair. S63. Randomly sample modules that have passed inspection and completed repairs, and conduct standard high and low temperature cycle aging tests and damp heat aging tests for a certain period of time. S64. After the aging test is completed, the module's photoelectric parameters, airtightness, and signal integrity are fully re-inspected. If all indicators meet the standards, it is judged to be a qualified product, and the optical module manufacturing is completed.

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