Preparation technology and application of a silicon-based microstrip circulator

Abstract

The present invention relates to the field of IPC B81C1 / 00, and in particular to a preparation process and application of a silicon-based microstrip circulator. The specific steps include: S1. Pre-treating a silicon wafer to obtain a first substrate; S2. Vacuum coating the first substrate to obtain a second substrate; S3. Etching the second substrate multiple times to obtain a third substrate; S4. Vacuum coating the third substrate twice to obtain a fourth substrate; S5. Debonding, laminating, welding, and cutting the fourth substrate to obtain a finished substrate; S6. Embedding magnetic materials in the substrate to obtain a silicon-based microstrip circulator; the first substrate is a disc structure with a cavity in the middle; one side of the disc structure is the welding surface of the first substrate, and the other side is the protective surface of the first substrate. The silicon-based microstrip circulator prepared by the present invention has the advantages of low working loss and wide temperature resistance, and can meet the needs of small integrated communication devices.

Description

Technical Field

[0001] The invention relates to the field of IPC B81C1 / 00, and in particular to a preparation process and application of a silicon-based microstrip circulator. Background Art

[0002] Since the 21st century, the field of communication technology has been undergoing earth-shaking changes. The progress of communication means such as radar, wireless communication, microwave communication and wireless local area network has promoted the development of communication systems towards miniaturization, integration, lightweight and high efficiency. Circulators are a type of communication device that integrates signal reception and transmission. They transmit the incident wave to the next port in the direction determined by the static bias magnetic field, so that the input signal is transported in a circular manner in sequence, and can effectively separate microwave signals of different frequencies; microwave ferrite devices made based on circulators are an important branch of wireless communication terminal products. According to different structures, circulators can be divided into microstrip, waveguide, stripline and coaxial types, among which microstrip circulators occupy a large share in the market; microstrip circulators use ferrite materials as transmission media embedded in the substrate for signal transmission, and the substrate has an important influence on the performance of the molded device. Chinese patent CN110171802A discloses a deep silicon etching method for MEMS, CN207069031U discloses a circulator and isolator, and CN103762160B discloses a deep silicon etching method and device. In the prior art, ceramics are usually used as substrates for ferrite magnetic materials, but ceramic substrates are brittle and have poor post-processing performance, which is difficult to match the development trend of precision and high-efficiency annular belts. In this context, the present invention uses a silicon substrate to encapsulate magnetic materials to obtain a microstrip circulator that can meet performance and size requirements. Summary of the invention

[0003] In order to solve the above problems, the first aspect of the present invention provides a preparation process of a silicon-based microstrip circulator, and the specific steps include:

[0004] S1. Pre-treating the silicon wafer to obtain a first substrate;

[0005] S2. vacuum coating the first substrate to obtain a second substrate;

[0006] S3. etching the second substrate multiple times to obtain a third substrate;

[0007] S4. Performing a secondary vacuum coating on the third substrate to obtain a fourth substrate;

[0008] S5. The fourth substrate is debonded, laminated, welded, and cut to obtain a finished substrate;

[0009] S6. Embedding magnetic material in the substrate to obtain a silicon-based microstrip circulator;

[0010] The first substrate is a disc structure with a cavity in the middle; one side of the disc structure is a welding surface of the first substrate, and the other side is a protection surface of the first substrate.

[0011] In some preferred embodiments, the size of the silicon wafer is 2-6 inches; the thickness of the silicon wafer is 0.2-1 mm.

[0012] In some preferred embodiments, the step S1 specifically includes performing deep silicon etching on the silicon wafer to obtain a silicon wafer containing a cavity structure, performing RCA cleaning on the silicon wafer containing the cavity structure to remove impurities in the silicon wafer, and obtaining a first substrate.

[0013] Further preferably, the deep silicon etching is one of laser etching, photo-assisted electrochemical etching, low temperature etching and plasma etching.

[0014] More preferably, the deep silicon etching is preferably plasma deep silicon etching; MEMS (micro-electromechanical system) is used to perform deep silicon etching on the silicon wafer. The specific steps include: placing the silicon wafer in a high-density plasma etcher, passing a passivation gas for passivation; then passing an etching gas for etching; repeating the passivation and etching operations 2-10 times. The coil power of the high-density plasma etcher is 300-1500W, and the plate power is 10-50W.

[0015] In some preferred embodiments, the passivation gas is C4F8, the introduction rate of the passivation gas is 60-200 mL / min, and the introduction time is 5-20 s; the etching gas is SF6, the introduction rate of the etching gas is 60-200 mL / min, and the introduction time is 3-10 s.

[0016] In some preferred embodiments, the specific steps of the RCA cleaning are: cleaning the silicon wafer after deep silicon etching with (1) an acidic hydrogen peroxide aqueous solution, (2) an alkaline hydrogen peroxide aqueous solution, (3) a hydrofluoric acid aqueous solution, and (4) a second acidic hydrogen peroxide aqueous solution in sequence; rinsing the silicon wafer with ultrapure water after each reagent cleaning, and after cleaning, rinsing with ultrapure water for 5-20 minutes, and drying to obtain a first substrate.

[0017] Further preferably, the acidic hydrogen peroxide aqueous solution is specifically a H2O2 aqueous solution containing H2SO4, wherein the volume ratio of H2SO4, H2O2 and water is 3:1:3; the cleaning temperature in step (1) is 100-135°C, and the cleaning time is 4-20min.

[0018] Further preferably, the alkaline hydrogen peroxide aqueous solution is specifically a H2O2 aqueous solution containing NH4OH, wherein the volume ratio of NH4OH, H2O2 and water is 1:1-2:5-7; the cleaning temperature in step (2) is 50-75°C, and the cleaning time is 3-10 min.

[0019] More preferably, the volume fraction of hydrofluoric acid in the hydrofluoric acid aqueous solution is 5-60%; the cleaning temperature in step (3) is 15-28° C., and the cleaning time is 3-24 min.

[0020] Further preferably, the second acidic hydrogen peroxide aqueous solution is specifically a H2O2 aqueous solution containing HCl, wherein the volume ratio of HCl, H2O2 and water is 1:1-2:6-8; the cleaning temperature in step (4) is 58-77°C and the cleaning time is 5-15 min.

[0021] In some preferred embodiments, the step S2 is specifically to vacuum coat the first substrate by sputtering, and the film layer on the welding surface is set to be one of Ti, Al, and Au, and the film layer on the protective surface is set to be one of Au, Cu, and Ni.

[0022] Further preferably, in the step S2, the film layer on the welding surface is a Ti film with a film thickness of 1-10 um, and the film layer on the protective surface is an Au film with a film thickness of 1-10 um.

[0023] In some preferred embodiments, the S2 step is specifically to place the first substrate in ethanol for ultrasonic cleaning for 3-5 minutes, and then purge nitrogen to dry. Place it in an ultra-high vacuum magnetron sputtering device, first use a Ti target to sputter the welding surface of the first substrate to form a film, and continuously introduce a mixed gas of high-purity helium and high-purity argon at a speed of 10-30mL / min during the sputtering process. The gas pressure ratio of high-purity helium and high-purity argon is (3-7): 1, and the gas pressure value of the mixed gas is 0.1-1Pa; then use an Au target to sputter the protective surface of the first substrate to form a film, and continuously introduce high-purity argon at a speed of 10-30mL / min during the sputtering process. The sputtering power is 50-300W, and the gas pressure value of the high-purity argon is 0.1Pa.

[0024] More preferably, the distance between the Ti target and the first substrate is 5-10 cm; the distance between the Au target and the first substrate is 15-25 cm.

[0025] In some preferred embodiments, the step S3 specifically includes sequentially performing a first photolithography, a chemical etching and a second photolithography on the second substrate; the chemical etching is a wet etching or a plasma etching.

[0026] Further preferably, the one photolithography operation in step S3 is to apply a photoresist to the welding surface of the second substrate, and obtain a finished product through ultraviolet light irradiation, development, hardening, etching and film stripping.

[0027] Further preferably, the chemical etching in the step S3 is wet etching; the wet etching is specifically, in a nitrogen atmosphere, contacting the second substrate after the first photolithography with an etching solution, reacting for 1-5 minutes, taking it out and rinsing it with ultrapure water, and blowing it dry with nitrogen.

[0028] More preferably, the etching solution is at least one of nitric acid, hydrofluoric acid, acetic acid, and phosphoric acid.

[0029] More preferably, the etching solution is a composition of hydrofluoric acid, nitric acid, acetic acid and water; the weight ratio of hydrofluoric acid, nitric acid, acetic acid and water is 50:2:0.5:1.

[0030] After the chemical etching in step S3 is completed, a secondary photolithography is performed, and the operation steps are the same as the primary photolithography, so that the pattern appears on the second substrate.

[0031] The photoresist was purchased from Xi'an Qiyue Biotechnology Co., Ltd.

[0032] In some preferred embodiments, the S4 step is specifically to perform secondary vacuum coating on the third substrate by sputtering, setting the film layer on the welding surface to one of Ti, Al, and Au, and the film layer on the protective surface to one of Au, Cu, and Ni.

[0033] In some preferred embodiments, during the secondary vacuum coating in step S4, the film layer on the welding surface is Ti, and the film layer on the protective surface is Au.

[0034] In some preferred embodiments, the S4 step is specifically to place the third substrate in ethanol for ultrasonic cleaning for 3-5 minutes, and then purge nitrogen to dry. Place it in an ultra-high vacuum magnetron sputtering device, first use a Ti target to sputter the welding surface of the third substrate to form a film, and continuously introduce a mixed gas of high-purity helium and high-purity argon at a speed of 10-30mL / min during the sputtering process. The gas pressure ratio of high-purity helium and high-purity argon is (3-7): 1, and the gas pressure value of the mixed gas is 0.1-1Pa; then use an Au target to sputter the protective surface of the third substrate to form a film, and continuously introduce high-purity argon at a speed of 10-30mL / min during the sputtering process. The sputtering power is 50-300W, and the gas pressure value of the high-purity argon is 0.1Pa.

[0035] In some preferred embodiments, the S5 step is specifically to remove the photoresist on the surface of the fourth substrate, and then take two fourth substrates and stack and align them in an aligner, with the welding surface of the two fourth substrates as the contact surface. After alignment, they are transferred to a vacuum welding machine for welding, and then cut and shaped using a grinding wheel divider to obtain a genuine substrate.

[0036] In some preferred embodiments, the welding temperature in step S5 is 200-450°C.

[0037] Specifically, the S6 step includes placing the fourth substrate in acetone for 3-30 minutes to remove the photoresist on the surface of the fourth substrate, and then taking two fourth substrates to stack and align them in an aligner, with the welding surfaces of the two fourth substrates being the contact surfaces. After alignment, the two fourth substrates are transferred to a vacuum welding machine for welding, and then cut and shaped using a grinding wheel divider to obtain a genuine substrate.

[0038] In some preferred embodiments, the properties of the cut and shaped substrate are not particularly limited and can be set according to actual conditions, such as triangle, quadrilateral, square, pentagon, hexagon, etc.

[0039] A second aspect of the present invention provides an application of a preparation process for a silicon-based microstrip circulator, wherein the preparation process is applied in the field of wireless communication technology.

[0040] Beneficial effects:

[0041] The silicon-based microstrip circulator prepared by the present invention has the advantages of low working loss and wide temperature resistance, which can meet the needs of small integrated communication devices. Through specific etching processes and processing methods, the return loss of the silicon-based microstrip circulator can be reduced to about 0.5dB, and the product has strong dimensional stability and can maintain precise dimensions under high and low temperature conditions, and has broad application prospects. DETAILED DESCRIPTION

[0042] Example 1.

[0043] This embodiment provides a process for preparing a silicon-based microstrip circulator, and the specific steps include:

[0044] S1. Pre-treating the silicon wafer to obtain a first substrate;

[0045] S2. vacuum coating the first substrate to obtain a second substrate;

[0046] S3. etching the second substrate multiple times to obtain a third substrate;

[0047] S4. Performing a secondary vacuum coating on the third substrate to obtain a fourth substrate;

[0048] S5. The fourth substrate is debonded, laminated, welded, and cut to obtain a finished substrate;

[0049] S6. Embedding magnetic material in the substrate to obtain a silicon-based microstrip circulator;

[0050] The first substrate is a disc structure with a cavity in the middle; one side of the disc structure is a welding surface of the first substrate, and the other side is a protection surface of the first substrate.

[0051] The step S1 specifically includes performing deep silicon etching on the silicon wafer to obtain a silicon wafer containing a cavity structure, performing RCA cleaning on the silicon wafer containing the cavity structure to remove impurities from the silicon wafer, and obtaining a first substrate.

[0052] The deep silicon etching is plasma deep silicon etching; MEMS (micro-electromechanical system) is used to perform deep silicon etching on silicon wafers. The specific steps include: placing the silicon wafer in a high-density plasma etcher, passing a passivation gas for passivation; then passing an etching gas for etching; repeating the passivation and etching operations 5 times. The coil power of the high-density plasma etcher is 1200W, and the plate power is 20W.

[0053] The passivation gas is C4F8, the introduction rate of the passivation gas is 100 mL / min, and the introduction time is 10 s; the etching gas is SF6, the introduction rate of the etching gas is 80 mL / min, and the introduction time is 8 s.

[0054] The specific steps of the RCA cleaning are: cleaning the silicon wafer after deep silicon etching with (1) an acidic hydrogen peroxide aqueous solution, (2) an alkaline hydrogen peroxide aqueous solution, (3) a hydrofluoric acid aqueous solution, and (4) a second acidic hydrogen peroxide aqueous solution in sequence; rinsing the silicon wafer with ultrapure water after each reagent cleaning, and after the cleaning is completed, rinsing with ultrapure water for 5-20 minutes, and drying to obtain a first substrate.

[0055] The acidic hydrogen peroxide aqueous solution is specifically a H2O2 aqueous solution containing H2SO4, wherein the volume ratio of H2SO4, H2O2 and water is 3:1:3; the cleaning temperature in step (1) is 124°C and the cleaning time is 15 minutes.

[0056] The alkaline hydrogen peroxide aqueous solution is specifically a H2O2 aqueous solution containing NH4OH, wherein the volume ratio of NH4OH, H2O2 and water is 1:1:6; the cleaning temperature in step (2) is 65°C and the cleaning time is 5 minutes.

[0057] The volume fraction of hydrofluoric acid in the hydrofluoric acid aqueous solution is 50%; the cleaning temperature in step (3) is 24° C. and the cleaning time is 6 minutes.

[0058] The second acidic hydrogen peroxide aqueous solution is specifically a H2O2 aqueous solution containing HCl, wherein the volume ratio of HCl, H2O2 and water is 1:2:7; the cleaning temperature in step (4) is 66°C and the cleaning time is 10 minutes.

[0059] The step S2 is specifically to vacuum coat the first substrate by sputtering, the film layer on the welding surface is a Ti film with a thickness of 5 um, and the film layer on the protective surface is an Au film with a thickness of 5 um.

[0060] The S2 step is specifically as follows: ultrasonically clean the first substrate in ethanol for 5 minutes, then purge with nitrogen and dry it. Place it in an ultra-high vacuum magnetron sputtering device, first use a Ti target to sputter the welding surface of the first substrate to form a film, and continuously introduce a mixed gas of high-purity helium and high-purity argon at a rate of 20 mL / min during the sputtering process, the gas pressure ratio of high-purity helium and high-purity argon is 5:1, and the gas pressure value of the mixed gas is 1 Pa; then use an Au target to sputter the protective surface of the first substrate to form a film, and continuously introduce high-purity argon at a rate of 20 mL / min during the sputtering process, the sputtering power is 200 W, and the gas pressure value of the high-purity argon is 0.1 Pa.

[0061] In the step S2, the distance between the Ti target and the first substrate is 8 cm; the distance between the Au target and the first substrate is 20 cm.

[0062] The step S3 specifically includes sequentially performing primary photolithography, chemical etching and secondary photolithography on the second substrate; the chemical etching is wet etching or plasma etching.

[0063] The first photolithography operation in step S3 is to apply photoresist to the welding surface of the second substrate, and then obtain the finished product through ultraviolet light irradiation, development, hardening, etching and film stripping.

[0064] The chemical etching in step S3 is wet etching; the wet etching is specifically, in a nitrogen atmosphere, the second substrate after the first photolithography is contacted with an etching solution, reacted for 3 minutes, taken out and rinsed with ultrapure water, and blown dry with nitrogen.

[0065] The etching solution is a composition of hydrofluoric acid, nitric acid, acetic acid and water; the weight ratio of hydrofluoric acid, nitric acid, acetic acid and water is 50:2:0.5:1.

[0066] After the chemical etching in step S3 is completed, a secondary photolithography is performed, and the operation steps are the same as the primary photolithography, so that the pattern appears on the second substrate.

[0067] The photoresist was purchased from Xi'an Qiyue Biotechnology Co., Ltd.

[0068] The S4 step is specifically as follows: ultrasonically clean the third substrate in ethanol for 5 minutes, then purge with nitrogen and dry it. Place the substrate in an ultra-high vacuum magnetron sputtering device, first use a Ti target to sputter the welding surface of the third substrate to form a film, and continuously introduce a mixed gas of high-purity helium and high-purity argon at a speed of 20 mL / min during the sputtering process, the gas pressure ratio of high-purity helium and high-purity argon is 5:1, and the gas pressure value of the mixed gas is 1 Pa; then use an Au target to sputter the protective surface of the third substrate to form a film, and continuously introduce high-purity argon at a speed of 20 mL / min during the sputtering process, the sputtering power is 200 W, and the gas pressure value of the high-purity argon is 0.1 Pa.

[0069] In the step S4, the distance between the Ti target and the third substrate is 8 cm; the distance between the Au target and the third substrate is 20 cm.

[0070] Specifically, the step S5 is to remove the photoresist on the surface of the fourth substrate, and then take two fourth substrates to stack and align them in an aligner, with the welding surface of the two fourth substrates as the contact surface. After alignment, the two fourth substrates are transferred to a vacuum welding machine for welding, and then cut and shaped with a grinding wheel divider to obtain a genuine substrate.

[0071] The soldering temperature in step S5 is 300°C.

[0072] Specifically, the S6 step is to place the fourth substrate in acetone for 10 minutes to remove the residual photoresist on the surface of the fourth substrate, and then take two fourth substrates to stack and align them in an aligner, with the welding surface of the two fourth substrates as the contact surface. After alignment, the two fourth substrates are transferred to a vacuum welding machine for welding, and then cut and shaped using a grinding wheel divider to obtain a genuine substrate.

[0073] The silicon wafer has a size of 4 inches and a thickness of 0.5 mm, and is sourced from Suzhou Huaqinyuan Microelectronics Technology Co., Ltd.; the magnetic material is a ferrite sheet, and is sourced from Suzhou Huaqinyuan Microelectronics Technology Co., Ltd.

[0074] Example 2.

[0075] This embodiment provides a preparation process of a silicon-based microstrip circulator, and the specific implementation method is the same as that of Example 1; the difference is that the passivation gas is C4F8, the introduction rate of the passivation gas is 50mL / min, and the introduction time is 20s.

[0076] Example 3.

[0077] This embodiment provides a preparation process of a silicon-based microstrip circulator, and the specific implementation method is the same as that of Example 1; the difference is that the etching gas is SF6, the introduction rate of the etching gas is 120 mL / min, and the introduction time is 5 s.

[0078] Example 4.

[0079] The present embodiment provides a preparation process of a silicon-based microstrip circulator, and the specific implementation method is the same as that of Example 1; the difference is that in the S2 step, a Ti target is used to sputter and form a film on the welding surface of the first substrate, and a mixed gas of high-purity helium and high-purity argon is continuously introduced at a rate of 20 mL / min during the sputtering process. The gas pressure ratio of high-purity helium and high-purity argon is 5:1, and the gas pressure value of the mixed gas is 3 Pa.

[0080] Example 5.

[0081] The present embodiment provides a preparation process of a silicon-based microstrip circulator, and the specific implementation method is the same as that of Example 1; the difference is that in the S2 step, a Ti target is used to sputter and form a film on the welding surface of the first substrate, and a mixed gas of high-purity helium and high-purity argon is continuously introduced at a rate of 40 mL / min during the sputtering process. The gas pressure ratio of high-purity helium and high-purity argon is 5:1, and the gas pressure value of the mixed gas is 1 Pa.

[0082] Example 6.

[0083] The present embodiment provides a preparation process of a silicon-based microstrip circulator, and the specific implementation method is the same as that of Example 1; the difference is that in the S2 step, a Ti target is used to sputter and form a film on the welding surface of the first substrate, and a mixed gas of high-purity helium and high-purity argon is continuously introduced at a rate of 20 mL / min during the sputtering process. The gas pressure ratio of high-purity helium and high-purity argon is 9:1, and the gas pressure value of the mixed gas is 3 Pa.

[0084] Performance Testing Methods

[0085] Wear resistance:

[0086] The silicon-based microstrip circulators of Examples 1-6 were placed at 24 GHz to measure their return losses; each group of samples was measured 10 times in parallel and the average value was taken.

[0087] High temperature resistance:

[0088] The silicon-based microstrip circulator of Example 1-10 was placed at 60° C. for 24 hours, and then taken out and the thickness was tested at 5 points randomly selected on the finished substrate. The relative standard deviation (RSD) of the thickness results at the 5 points was calculated. h Each group of samples was measured 10 times in parallel and the average value was taken.

[0089] Low temperature resistance:

[0090] The silicon-based microstrip circulators of Examples 1-6 were placed at -10°C for 24 hours, and then taken out and the thickness was tested at 5 points randomly selected on the finished substrate. The relative standard deviation (RSD) of the thickness results at the 5 points was calculated. c Each group of samples was measured 10 times in parallel and the average value was taken.

[0091] Performance test data

[0092] Table 1. Performance test results

[0093] Return loss dB <![CDATA[RSD h %]]> <![CDATA[RSD c %]]> Example 1 0.52 2.5 1.1 Example 2 0.76 5.8 3.7 Example 3 0.86 6.4 4.6 Example 4 0.91 6.9 5.1 Example 5 0.75 5.2 3.6 Example 6 0.96 6.6 4.8

Claims

1. A process for preparing a silicon-based microstrip circulator, characterized in that: The specific steps include: S1. Pre-treating the silicon wafer to obtain a first substrate; S2. vacuum coating the first substrate to obtain a second substrate; S3. etching the second substrate multiple times to obtain a third substrate; S4. Performing a secondary vacuum coating on the third substrate to obtain a fourth substrate; S5. The fourth substrate is debonded, laminated, welded, and cut to obtain a finished substrate; S6. Embedding magnetic material in the substrate to obtain a silicon-based microstrip circulator; The first substrate is a disc structure with a cavity in the middle; one side of the disc structure is a welding surface of the first substrate, and the other side is a protection surface of the first substrate; The step S2 specifically includes: vacuum coating the first substrate by sputtering; setting the film layer of the welding surface to be a Ti film with a film thickness of 1-10 um; and setting the film layer of the protective surface to be an Au film with a film thickness of 1-10 um; Specifically, the S2 step comprises placing the first substrate in ethanol for ultrasonic cleaning for 3-5 minutes, and then blowing nitrogen to dry; placing the first substrate in an ultra-high vacuum magnetron sputtering device, firstly using a Ti target to sputter a film on the welding surface of the first substrate, and continuously introducing a mixed gas of high-purity helium and high-purity argon at a speed of 10-30 mL / min during the sputtering process, wherein the gas pressure ratio of the high-purity helium and the high-purity argon is (3-7):1, and the gas pressure value of the mixed gas is 0.1-1 Pa; then using an Au target to sputter a film on the protective surface of the first substrate, and continuously introducing high-purity argon at a speed of 10-30 mL / min during the sputtering process, wherein the sputtering power is 50-300 W, and the gas pressure value of the high-purity argon is 0.1 Pa; during the secondary vacuum coating in the S4 step, the film layer on the welding surface is Ti, and the film layer on the protective surface is Au; The S4 step is specifically as follows: placing the third substrate in ethanol for ultrasonic cleaning for 3-5 minutes, and then purging it with nitrogen to dry it; placing it in an ultra-high vacuum magnetron sputtering device, first using a Ti target to sputter and form a film on the welding surface of the third substrate, and continuously introducing a mixed gas of high-purity helium and high-purity argon at a speed of 10-30mL / min during the sputtering process, the gas pressure ratio of high-purity helium and high-purity argon is (3-7): 1, and the gas pressure value of the mixed gas is 0.1-1Pa; then using an Au target to sputter and form a film on the protective surface of the third substrate, and continuously introducing high-purity argon at a speed of 10-30mL / min during the sputtering process, the sputtering power is 50-300W, and the gas pressure value of the high-purity argon is 0.1Pa.

2. The process for preparing a silicon-based microstrip circulator according to claim 1, characterized in that: The step S1 specifically includes performing deep silicon etching on the silicon wafer to obtain a silicon wafer containing a cavity structure, performing RCA cleaning on the silicon wafer containing the cavity structure to remove impurities from the silicon wafer, and obtaining a first substrate.

3. The process for preparing a silicon-based microstrip circulator according to claim 1, characterized in that: The step S3 specifically includes sequentially performing primary photolithography, chemical etching and secondary photolithography on the second substrate; the chemical etching is wet etching or plasma etching.

4. The process for preparing a silicon-based microstrip circulator according to claim 1, characterized in that: Specifically, the step S5 is to remove the photoresist on the surface of the fourth substrate, and then take two fourth substrates to stack and align them in an aligner, with the welding surface of the two fourth substrates as the contact surface. After alignment, the two fourth substrates are transferred to a vacuum welding machine for welding, and then cut and shaped with a grinding wheel divider to obtain a genuine substrate.

5. The process for preparing a silicon-based microstrip circulator according to claim 4, characterized in that: The soldering temperature in step S5 is 200-450°C.

6. An application of the preparation process of a silicon-based microstrip circulator according to any one of claims 1 to 5, characterized in that: The preparation process is applied in the field of wireless communication technology.