A method and system for manufacturing ultra-small AWG chips

Abstract

This invention relates to a method and system for fabricating an ultra-small AWG chip, comprising: using ICP-VD technology on a silicon substrate to controllably grow a low-stress, low-optical-absorption silicon nitride thin film by adjusting plasma power and gas flow rate; covering the silicon nitride thin film with a hybrid mask, and determining a reactive ion etching combination with a primary etching gas and an auxiliary passivation gas according to a target volume ratio; etching the silicon nitride thin film based on the reactive ion etching combination to form a silicon nitride waveguide structure with a sidewall roughness less than a preset roughness threshold; adjusting the thickness and width of the waveguide to achieve a design goal of ultra-thin and ultra-wide waveguide compatible with single-mode transmission characteristics and low bending loss, and designing the bending transition section of the waveguide as a gradually curved structure by transforming optical principles; integrating the designed waveguide into the AWG chip in a preset array configuration, and using a Rowland circle overlapping lithography to compress the overlapping area between the input and output waveguides in the array.

Description

Technical Field

[0001] This invention relates to the fields of optical communication technology and photonic integration technology, and in particular to a method and system for manufacturing an ultra-small AWG chip. Background Technology

[0002] Silicon nitride ( As a broadband transparent optical waveguide material with a high refractive index difference, it has significant advantages in ultra-small arrayed waveguide grating (AWG) chips, such as low transmission loss, wide transparency window, high refractive index contrast, and excellent thermal stability, making it the core material for achieving high-density integration and low-power operation in ultra-small AWG chips.

[0003] However, existing technologies face two major challenges: first, the light scattering loss and crosstalk caused by the roughness of the waveguide sidewalls; and second, the manufacturing process of waveguides with small bending radii is difficult to balance low loss and standardized production.

[0004] Currently, traditional etching processes are used to specifically process the sidewalls and curved parts of waveguides to solve the above problems. Although this gives the waveguides the initial shape and function, it also leads to insufficient control of sidewall roughness and lacks a standardized manufacturing process for ultra-small AWG chips, which restricts the application needs of scenarios such as data center optical interconnects. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method and system for manufacturing ultra-small AWG chips, which addresses the shortcomings of the prior art.

[0006] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A method for manufacturing an ultra-small AWG chip, the method comprising:

[0007] S1. Using ICPCVD technology on a silicon substrate, silicon nitride thin films with low stress and low optical absorption are controllably grown by adjusting plasma power and gas flow rate.

[0008] S2. A hybrid mask with a dielectric and metal bilayer structure is applied to a silicon nitride thin film, and the ratio is determined according to the target volume ratio. The main etching gas, with A reactive ion etching combination to assist passivation gas;

[0009] S3. Based on the reactive ion etching combination, the silicon nitride thin film is etched to form a silicon nitride waveguide structure with a sidewall roughness less than a preset roughness threshold.

[0010] S4. Under the target of ultra-thin and ultra-wide waveguide that is compatible with single-mode transmission characteristics and low bending loss, the thickness and width of the silicon nitride waveguide structure are adjusted, and the bending transition section of the silicon nitride waveguide structure is designed as a gradually bending structure by means of transformation optics.

[0011] S5. The designed silicon nitride waveguide structure is integrated into the AWG chip according to the preset array form, and the overlapping area between the input waveguide and the output waveguide in the array is compressed by using Roland circle overlapping PCB layout, so as to reduce the chip size and suppress crosstalk from the spatial layout.

[0012] Furthermore, in step S1, during the controllable growth of a silicon nitride thin film with low stress and low optical absorption, the method includes: adjusting the radio frequency power through closed-loop control within a preset radio frequency power range to optimize the plasma energy distribution, wherein a uniform and stable plasma energy distribution is used to ensure the regular arrangement of atoms in the silicon nitride thin film, thereby reducing defects, lowering light absorption, and controlling stress.

[0013] Furthermore, in step S1, during the controllable growth of a low-stress and low-optical-absorption silicon nitride thin film, the method further includes: adjusting the flow ratio of silicon source gas to nitrogen source gas according to closed-loop feedback, and / or introducing dilution gas to adjust plasma density, so as to ensure that the stoichiometry of the thin film reaches equilibrium and achieve synergistic control of the thin film growth rate and stress.

[0014] Furthermore, in step S2, according to Target volume ratio determined by The main etching gas, with A reactive ion etching combination to assist passivation gas.

[0015] Furthermore, in step S2, in Based on this target volume ratio, the method further includes: dynamically adjusting the target volume ratio using a comprehensive optimization strategy based on thin film characteristics and process requirements, and determining the volume ratio according to the adjusted volume ratio. The main etching gas, with A reactive ion etching combination to assist passivation gas.

[0016] Furthermore, in step S4, the thickness and width of the waveguide are adjusted in the following way: Given that the refractive index difference between the silicon nitride waveguide core and cladding is greater than a preset refractive index difference threshold, the thickness and width of the silicon nitride waveguide structure are used as the parameter optimization targets. Within the parameter constraints of the thickness being less than a preset thickness threshold and the width being greater than a preset width threshold, iterative optimization is performed with compatibility with single-mode transmission characteristics and low bending loss as the optimization guide. At the end of the iteration, the optimal combination of thickness and width parameters is obtained, and the thickness and width of the silicon nitride waveguide structure are adjusted based on this optimal parameter combination.

[0017] Furthermore, in step S4, the method further includes: designing the curved transition section of the waveguide as a gradually curved structure with target gradually changing bending parameters by transforming optical principles, so as to avoid additional losses caused by optical field leakage under small bending radius, wherein the target gradually changing bending parameters include bending angle, bending radius, and transmission loss.

[0018] Furthermore, in step S5, the method further includes: integrating the designed waveguides into an AWG chip according to an arc-shaped equidistant array, a linear compression array, or a segmented gradient array, and using a Roland circle overlapping PCB layout to compress the overlapping area between the input waveguides and the output waveguides in the array to below the target size, thereby suppressing crosstalk from a spatial layout perspective.

[0019] Secondly, this application discloses an ultra-small AWG chip fabrication system, the system comprising a silicon nitride thin film growth control module, a silicon nitride thin film etching module, a silicon nitride waveguide structure design module, and a waveguide integration and crosstalk suppression module, wherein:

[0020] The silicon nitride thin film growth control module is used to controllably grow low-stress and low-optical-absorption silicon nitride thin films on silicon substrates by adjusting plasma power and gas flow rate using ICPCVD technology.

[0021] The silicon nitride thin film etching module is used to cover a hybrid mask with a dielectric and metal bilayer structure onto a silicon nitride thin film, and to determine the etching ratio according to the target volume ratio. The main etching gas, with A reactive ion etching combination to assist passivation gas;

[0022] The silicon nitride thin film etching module is also used to etch the silicon nitride thin film based on the reactive ion etching combination to form a silicon nitride waveguide structure with a sidewall roughness less than a preset roughness threshold.

[0023] The silicon nitride waveguide structure design module is used to adjust the thickness and width of the silicon nitride waveguide structure under the design goals of compatibility with single-mode transmission characteristics and low bending loss of ultra-thin and ultra-wide waveguides, and to design the bending transition section of the silicon nitride waveguide structure as a gradually bending structure through the principle of transformation optics.

[0024] The waveguide integration and crosstalk suppression module is used to integrate the designed silicon nitride waveguide structure into the AWG chip in a preset array form, and to use Roland circle overlapping PCB layout to compress the overlapping area between the input waveguide and the output waveguide in the array, so as to suppress crosstalk from the spatial layout while reducing the chip size.

[0025] The beneficial effects of this invention are as follows: by using ICP-VD technology to controllably grow low-stress, low-optical-absorption silicon nitride thin films on silicon substrates, and using specific reactive ion etching combinations to form silicon nitride waveguide structures with small sidewall roughness, the waveguide parameters are adjusted and a gradient bending structure is designed according to the requirements of ultra-thin and ultra-wide waveguide design. Finally, the waveguide is integrated into an AWG chip and the PCB layout is optimized. After these steps are implemented, the chip size can be reduced while taking into account single-mode transmission and low bending loss characteristics, and crosstalk can be effectively suppressed, achieving good and efficient etching and passivation effects. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating a method for manufacturing an ultra-small AWG chip disclosed in this invention.

[0027] Figure 2 This is a schematic diagram of the structure of an ultra-small AWG chip manufacturing system disclosed in this invention. Detailed Implementation

[0028] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0029] like Figure 1 As shown, a method for manufacturing an ultra-small AWG chip includes:

[0030] Step S1: Using ICPCVD technology, silicon nitride thin films with low stress and low optical absorption are controllably grown on a silicon substrate by adjusting plasma power and gas flow rate.

[0031] Step S2: A hybrid mask with a dielectric and metal bilayer structure is applied to a silicon nitride thin film, and the ratio is determined according to the target volume ratio. The main etching gas, with A reactive ion etching combination to assist passivation gas.

[0032] Step S3: Based on the reactive ion etching combination, the silicon nitride thin film is etched to form a silicon nitride waveguide structure with a sidewall roughness less than a preset roughness threshold.

[0033] Specifically, this application uses the reactive ion etching combination to etch a silicon nitride thin film to form a silicon nitride waveguide structure with a sidewall roughness of less than 3 nm.

[0034] Step S4: Under the design goal of ultra-thin and ultra-wide waveguide that can be compatible with single-mode transmission characteristics and low bending loss, the thickness and width of the silicon nitride waveguide structure are adjusted, and the bending transition section of the silicon nitride waveguide structure is designed as a gradually bending structure by transforming the optical principle.

[0035] Step S5: The designed silicon nitride waveguide structure is integrated into the AWG chip according to a preset array form, and the overlapping area between the input waveguide and the output waveguide in the array is compressed by using Roland circle overlapping PCB layout, so as to reduce the chip size and suppress crosstalk from the spatial layout.

[0036] As can be seen from the above, the method for fabricating an ultra-small AWG chip disclosed in this application involves the controlled growth of a low-stress, low-optical-absorption silicon nitride thin film on a silicon substrate using ICP-VD technology, the formation of a silicon nitride waveguide structure with low sidewall roughness using a specific reactive ion etching combination, the adjustment of waveguide parameters and the design of a gradient bending structure according to the requirements of ultra-thin and ultra-wide waveguide design, and finally the integration of the waveguide into the AWG chip and optimization of the PCB layout. After these steps are implemented, the chip size can be reduced while taking into account single-mode transmission, low bending loss characteristics, and effectively suppressing crosstalk, achieving good and efficient etching and passivation effects.

[0037] In one embodiment, in step S1, during the controllable growth of a silicon nitride thin film with low stress and low optical absorption, the method includes: adjusting the radio frequency power through closed-loop control within a preset radio frequency power range to optimize the plasma energy distribution, wherein a uniform and stable plasma energy distribution is used to ensure the regular arrangement of atoms in the silicon nitride thin film, thereby reducing defects, lowering light absorption, and controlling stress.

[0038] Specifically, this application adopts a preset radio frequency power range of [100W, 300W], mainly because within this power range, ion energy and density can reach a relatively ideal balance, thereby avoiding excessive ion bombardment due to excessive power or insufficient film density due to excessive power. Ultimately, by controlling the obtained stable low to medium power (e.g., around 200W, with power fluctuations controlled within ±10W), the atomic arrangement of the silicon nitride film can be ensured to be regular, reducing absorption losses caused by internal material defects, resulting in excellent optical performance of the fabricated silicon nitride waveguide.

[0039] In one embodiment, in step S1, during the controllable growth of a low-stress and low-optical-absorption silicon nitride thin film, the method further includes: adjusting the flow ratio of silicon source gas to nitrogen source gas according to closed-loop feedback, and / or introducing dilution gas to adjust plasma density, so as to ensure that the stoichiometry of the thin film reaches equilibrium and achieve synergistic control of the thin film growth rate and stress.

[0040] Specifically, in the closed-loop feedback regulation process, this application utilizes a gas flow controller to direct the silicon source gas (such as...) ) and nitrogen source gas (such as The flow ratio is controlled near the theoretical optimal value of 1:3 to 1:5.

[0041] Furthermore, this application will utilize plasma diagnostic equipment to monitor plasma density in real time, and introduce an appropriate amount of dilution gas (such as...) based on the monitoring results. ), to stabilize the plasma density at Within this range.

[0042] In one embodiment, the overall gas flow rate is controlled at a low to medium level of 50 to 150 sccm to ensure sufficient reaction on the substrate surface and uniform film growth.

[0043] Finally, the above treatment yields a silicon nitride thin film with low optical absorption (<0.1dB / cm) and low stress (<50MPa).

[0044] In one embodiment, in step S2, according to Target volume ratio determined by The main etching gas, with A reactive ion etching combination to assist passivation gas.

[0045] Specifically, the reason why this application chose Main etching gas The combination of auxiliary passivating gases is mainly considered Capable of decomposing to produce ion, Due to their strong reactivity, ions can act as silicon nitride. Highly efficient etchants (such as those that can quickly break Si-N bonds) can further ensure etching efficiency. Can be used with etching products (such as) The reaction with trace impurities in the substrate forms a thin oxide layer. This thin oxide layer can passivate and protect the waveguide sidewalls, preventing the increase in roughness caused by excessive etching of the sidewalls and further controlling the sidewall quality.

[0046] Specifically, the reason why this application considers the target volume ratio of 4:1 is mainly because at this ratio... The number of F⁻ ions produced by decomposition and The passivation effect can achieve a good balance, ultimately achieving the dual goals of performance and process stability.

[0047] In one embodiment, in step S2, in Based on this target volume ratio, the method further includes: dynamically adjusting the target volume ratio using a comprehensive optimization strategy based on thin film characteristics and process requirements, and determining the volume ratio according to the adjusted volume ratio. The main etching gas, with A reactive ion etching combination to assist passivation gas.

[0048] Specifically, in the etching process of silicon nitride thin films, the initial... The volume ratio is 4:1. Considering that the characteristics of the silicon nitride film deposited by ICP-VD affect the etching effect, especially the film's density, a porous film has a less compact structure and is more easily eroded by etching gases during the etching process. If etching is performed according to the initial ratio, over-etching may occur. Therefore, this application will fine-tune the volume ratio based on the film's density, for example, adjusting the ratio to 3.5:1 to avoid over-etching.

[0049] Specifically, to meet the requirements for protecting hybrid masks, etch selectivity needs to be improved during the etching process to prevent over-etching of the hybrid mask. Etching selectivity largely depends on… and Therefore, this application will adjust the air intake flow rate of the two to control their volume ratio during the reactive ion etching process.

[0050] Specifically, to ensure process consistency, optimizing the volume ratio also requires stabilizing the total etching gas flow rate. This is because the stability of the total etching gas flow rate directly affects the stability of the etching environment. Large fluctuations in the total flow rate can lead to significant differences in etching results between batches. For example, controlling the total etching gas flow rate at 50-100 sccm can ensure that the etching fluctuation between batches is less than 5%, and meets standardized manufacturing requirements.

[0051] In summary, the desired waveguide structure can be formed by etching silicon nitride thin films using an optimized volume ratio. This reduces the roughness of the waveguide sidewalls to below 3 nm and the transmission loss to 0.05 dB / cm.

[0052] In one embodiment, in step S4, the thickness and width of the waveguide are adjusted in the following way: taking the refractive index difference between the silicon nitride waveguide core layer and the cladding layer being greater than a preset refractive index difference threshold as the core premise, taking the thickness and width of the silicon nitride waveguide structure as the parameter optimization target, and within the parameter constraint range where the thickness is less than a preset thickness threshold and the width is greater than a preset width threshold, iterative optimization is performed with the optimization guide of being compatible with single-mode transmission characteristics and low bending loss as the optimization direction. At the end of the iteration, the optimal combination of thickness and width parameters is obtained, and the thickness and width of the silicon nitride waveguide structure are adjusted based on the optimal parameter combination.

[0053] Specifically, this application takes the refractive index difference between the silicon nitride waveguide core layer and the cladding layer being greater than 0.3 as the core premise, takes the thickness and width of the silicon nitride waveguide structure as the parameter optimization targets, and performs iterative optimization within the parameter constraints of a thickness of less than 200 nm and a width of greater than 2 μm.

[0054] It should be noted that this is mainly because when the refractive index difference is greater than 0.3, the light field will be more effectively confined to the core region of the silicon nitride waveguide, reducing the leakage of light energy to the substrate and cladding, thereby improving the light transmission efficiency.

[0055] It should be noted that this application designs multiple combinations of thickness and width parameters within the parameter constraints of a thickness less than 200 nm and a width greater than 2 μm. Then, based on these parameter combinations, the optical field distribution within the waveguide is calculated using finite element simulation. When the simulation determines that the fundamental mode accounts for more than 99% of the optical field and the higher-order modes account for less than 1%, the single-mode transmission condition is deemed met.

[0056] In addition, this application will determine the minimum bending radius based on the parameter combination, and simulate the optical transmission of the waveguide under the minimum bending radius through finite element simulation. When the 90° bending radius is less than 2 mm, the transmission loss is less than 0.02 dB, which is determined to meet the low bending loss requirement.

[0057] It should be noted that this application is based on the refractive index difference between the silicon nitride waveguide core layer and the cladding layer being greater than 0.3. Combined with an "ultra-thin (height < 200 nm) and ultra-wide (width > 2 μm)" waveguide structure, the light field height can be more concentrated in the waveguide core region. By reducing the light field overflow to the sidewalls and the outside, the probability of light field coupling with adjacent waveguides is reduced.

[0058] In one embodiment, in step S4, the method further includes: designing the curved transition section of the waveguide as a gradually curved structure with target gradually changing bending parameters by transforming optical principles, so as to avoid additional losses caused by optical field leakage under small bending radius, wherein the target gradually changing bending parameters include bending angle, bending radius, and transmission loss.

[0059] In one embodiment, step S5 further includes: integrating the designed waveguides into an AWG chip according to an arc-shaped equidistant array, a linear compression array, or a segmented gradient array, and using a Roland circle overlapping PCB layout to compress the overlapping area between the input waveguides and the output waveguides in the array to below the target size, thereby suppressing crosstalk from a spatial layout perspective.

[0060] It should be noted that this application compresses the overlapping area between the input waveguide and the output waveguide in the array to less than 500 μm, thereby suppressing crosstalk from a spatial layout perspective.

[0061] Specifically, the Roland circle overlapping lithography, based on its unique geometric optical properties, can precisely control the propagation path of light in the waveguide. When this lithography method is used to compress the overlapping area of ​​the waveguide, the propagation mode of light within the overlapping area changes. The mutual penetration and coupling of light fields that might have occurred due to an excessively large overlapping area are effectively suppressed, because the compressed overlapping area allows the light fields of different waveguides to be more clearly separated in space, thereby suppressing crosstalk from a spatial layout perspective.

[0062] It should be noted that the arc-shaped equidistant array is specifically designed with the center of the Rowland circle as the arc center, arranging the input / output waveguides in an arc-shaped array with equal angular spacing. The outgoing / incoming ends of the waveguides precisely point towards the grating region on the Rowland circle. This arrangement maximizes the matching with the AWG's beam splitting principle and reduces losses caused by optical path offset. The linear compression array is specifically a waveguide array arranged linearly along the short side of the chip. High-density integration is achieved by reducing the spacing between adjacent waveguides. Combined with a design that compresses the overlapping area to below 500μm, more channels can be arranged within a limited chip area, while crosstalk is suppressed through spacing optimization. The segmented gradient array uses an equidistant linear arrangement at the waveguide input end for easy coupling with the fiber array; the transition section uses a gradient spacing design, smoothly converging to the arc-shaped arrangement corresponding to the Rowland circle grating. This balances coupling convenience and compatibility with the beam splitting structure, and the gradient transition further reduces bending loss.

[0063] Please refer to Figure 2 This application discloses an ultra-small AWG chip fabrication system, which includes a silicon nitride thin film growth control module, a silicon nitride thin film etching module, a silicon nitride waveguide structure design module, and a waveguide integration and crosstalk suppression module, wherein:

[0064] The silicon nitride thin film growth control module is used to controllably grow low-stress and low-optical-absorption silicon nitride thin films on silicon substrates by adjusting plasma power and gas flow rate using ICPCVD technology.

[0065] The silicon nitride thin film etching module is used to cover a hybrid mask with a dielectric and metal bilayer structure onto a silicon nitride thin film, and to determine the etching ratio according to the target volume ratio. The main etching gas, with A reactive ion etching combination to assist passivation gas.

[0066] The silicon nitride thin film etching module is also used to etch the silicon nitride thin film based on the reactive ion etching combination to form a silicon nitride waveguide structure with a sidewall roughness less than a preset roughness threshold.

[0067] The silicon nitride waveguide structure design module is used to adjust the thickness and width of the silicon nitride waveguide structure under the design goals of compatibility with single-mode transmission characteristics and low bending loss of ultra-thin and ultra-wide waveguides, and to design the bending transition section of the silicon nitride waveguide structure as a gradually bending structure through the principle of transformation optics.

[0068] The waveguide integration and crosstalk suppression module is used to integrate the designed silicon nitride waveguide structure into the AWG chip in a preset array form, and to use Roland circle overlapping PCB layout to compress the overlapping area between the input waveguide and the output waveguide in the array, so as to suppress crosstalk from the spatial layout while reducing the chip size.

[0069] In one embodiment, the above modules are also used to implement a method for manufacturing an ultra-small AWG chip as described in any of the foregoing method embodiments, and this application does not limit this.

[0070] As can be seen from the above, the ultra-small AWG chip fabrication system disclosed in this application achieves low-stress, low-optical-absorption silicon nitride thin films on silicon substrates using ICP-CVD technology, forms silicon nitride waveguide structures with low sidewall roughness using specific reactive ion etching combinations, adjusts waveguide parameters and designs a gradient bending structure according to the requirements of ultra-thin and ultra-wide waveguide design, and finally integrates the waveguide into the AWG chip and optimizes the PCB layout. After these steps are implemented, the chip size can be reduced while taking into account single-mode transmission, low bending loss characteristics, and effectively suppressing crosstalk, achieving good and efficient etching and passivation effects.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of fabricating an ultrasmall AWG chip, characterized by, The method includes: S1. Using ICPCVD technology on a silicon substrate, a low-stress and low-optical-absorption silicon nitride thin film is controllably grown by adjusting plasma power and gas flow rate to ensure the regular atomic arrangement of the silicon nitride thin film, thereby reducing defects, lowering light absorption, and controlling stress. During the controllable growth of the low-stress and low-optical-absorption silicon nitride thin film, the method further includes: adjusting the radio frequency power through closed-loop control within a preset radio frequency power range to optimize the plasma energy distribution. A uniform and stable plasma energy distribution is used to ensure the regular atomic arrangement of the silicon nitride thin film, thereby reducing defects, lowering light absorption, and controlling stress. S2. A hybrid mask with a dielectric and metal bilayer structure is applied to a silicon nitride thin film, according to… Target volume ratio determined by The main etching gas, with To assist the reactive ion etching combination of passivation gas, so as to passivate and protect the waveguide sidewalls and avoid the increase in roughness caused by excessive etching of the sidewalls; S3. Based on the reactive ion etching combination, the silicon nitride thin film is etched to form a silicon nitride waveguide structure with a sidewall roughness less than a preset roughness threshold, so as to reduce the light field overflow to the sidewall and the outside. S4. Under the design goal of ultra-thin and ultra-wide waveguides that are compatible with single-mode transmission characteristics and low bending loss, the thickness and width of the silicon nitride waveguide structure are adjusted, and the bending transition section of the silicon nitride waveguide structure is designed as a gradually bending structure by means of transformation optics. S5. The designed silicon nitride waveguide structure is integrated into the AWG chip according to the preset array form, and the overlapping area between the input waveguide and the output waveguide in the array is compressed to less than 500μm by using Roland circle overlapping PCB layout, so as to reduce the chip size and suppress crosstalk from the spatial layout. In step S1, during the controllable growth of a silicon nitride thin film with low stress and low optical absorption, the method includes: adjusting the radio frequency power through closed-loop control within a preset radio frequency power range to optimize the plasma energy distribution, wherein a uniform and stable plasma energy distribution is used to ensure the regular arrangement of atoms in the silicon nitride thin film, thereby reducing defects, lowering light absorption, and controlling stress. In step S4, the thickness and width of the waveguide are adjusted in the following way: with the refractive index difference between the silicon nitride waveguide core layer and the cladding layer being greater than 0.3, the thickness and width of the silicon nitride waveguide structure are used as the parameter optimization targets. Within the parameter constraints of a thickness of less than 200 nm and a width of greater than 2 μm, iterative optimization is carried out with compatibility with single-mode transmission characteristics and low bending loss as the optimization guide. At the end of the iteration, the optimal combination of thickness and width parameters is obtained, and the thickness and width of the silicon nitride waveguide structure are adjusted based on this optimal combination of thickness and width parameters.

2. The method according to claim 1, characterized in that, In step S2, Based on this target volume ratio, the method further includes: dynamically adjusting the target volume ratio using a comprehensive optimization strategy based on thin film characteristics and process requirements, and determining the volume ratio according to the adjusted volume ratio. The main etching gas, with A reactive ion etching combination to assist passivation gas.

3. The method according to claim 1, characterized in that, In step S4, the method further includes: designing the curved transition section of the waveguide as a gradually curved structure with target gradually changing bending parameters by transforming the optical principle, so as to avoid additional losses caused by optical field leakage under small bending radius, wherein the target gradually changing bending parameters include bending angle, bending radius, and transmission loss.

4. The method according to claim 1, characterized in that, In step S5, the method further includes: integrating the designed waveguides into an AWG chip according to an arc-shaped equidistant array, a linear compression array, or a segmented gradient array, and using a Roland circle overlapping PCB layout to compress the overlapping area between the input waveguides and the output waveguides in the array to below the target size, thereby suppressing crosstalk from a spatial layout perspective.

5. A system for fabricating ultra-small AWG chips, characterized in that, The system includes a silicon nitride thin film growth control module, a silicon nitride thin film etching module, a silicon nitride waveguide structure design module, and a waveguide integration and crosstalk suppression module, wherein: The silicon nitride thin film growth control module is used to controllably grow low-stress and low-optical-absorption silicon nitride thin films on silicon substrates using ICPCVD technology. By adjusting plasma power and gas flow rate, it ensures the regular atomic arrangement of the silicon nitride thin film, reduces defects, lowers light absorption, and controls stress. During the controllable growth of low-stress and low-optical-absorption silicon nitride thin films, the radio frequency power is adjusted through closed-loop control within a preset radio frequency power range to optimize the plasma energy distribution. The uniform and stable plasma energy distribution is used to ensure the regular atomic arrangement of the silicon nitride thin film, reducing defects, lowering light absorption, and controlling stress. The silicon nitride thin film etching module is used to cover a hybrid mask with a dielectric and metal bilayer structure onto a silicon nitride thin film, and according to... Target volume ratio determined by The main etching gas, with To assist the reactive ion etching combination of passivation gas, so as to passivate and protect the waveguide sidewalls and avoid the increase in roughness caused by excessive etching of the sidewalls; The silicon nitride thin film etching module is also used to etch the silicon nitride thin film based on the reactive ion etching combination to form a silicon nitride waveguide structure with a sidewall roughness less than a preset roughness threshold, so as to reduce the light field overflow to the sidewall and the outside. The silicon nitride waveguide structure design module is used to adjust the thickness and width of the silicon nitride waveguide structure under the design goals of compatibility with single-mode transmission characteristics and low bending loss of ultra-thin and ultra-wide waveguides, and to design the bending transition section of the silicon nitride waveguide structure as a gradually bending structure through the principle of transformation optics. The waveguide integration and crosstalk suppression module is used to integrate the designed silicon nitride waveguide structure into the AWG chip according to a preset array form, and adopts Roland circle overlapping PCB layout to compress the overlapping area between the input waveguide and the output waveguide in the array to less than 500μm, so as to suppress crosstalk from the spatial layout while reducing the chip size. In the process of controllable growth of silicon nitride thin films with low stress and low optical absorption, the silicon nitride thin film growth control module is also used to: adjust the radio frequency power through closed-loop control within a preset radio frequency power range to optimize the plasma energy distribution. The uniform and stable plasma energy distribution is used to ensure that the silicon nitride thin film atoms are arranged in a regular manner, thereby reducing defects, reducing light absorption and controlling stress. The silicon nitride waveguide structure design module adjusts the thickness and width of the waveguide in the following way: Given that the refractive index difference between the silicon nitride waveguide core and cladding is greater than a preset refractive index difference threshold, the module optimizes the thickness and width of the silicon nitride waveguide structure using these as parameters. Within the parameter constraints of a thickness less than a preset thickness threshold and a width greater than a preset width threshold, it iterative optimization is performed with compatibility with single-mode transmission characteristics and low bending loss as the optimization guide. At the end of the iteration, the optimal combination of thickness and width parameters is obtained, and the thickness and width of the silicon nitride waveguide structure are adjusted based on this optimal combination of thickness and width parameters.

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