Filter and its frequency modification method

Abstract

The application provides a filter and a frequency trimming method thereof, wherein the method comprises the following steps: forming a frequency trimming layer by depositing silicon dioxide on the surface of a wafer with a filter pattern; performing a first probe test on the wafer with the frequency trimming layer on the surface; thinning the frequency trimming layer to complete a first frequency trimming; performing a second probe test on the wafer after the first frequency trimming; sequentially performing a uniform coating, exposure and development on the wafer after the first frequency trimming; thinning the frequency trimming layer corresponding to the area of a series resonator of the filter on the wafer after the first frequency trimming to complete a second frequency trimming; and stripping the photoresist covering the surface of the parallel resonator on the wafer after the second frequency trimming. The filter frequency trimming method can ensure that the filter does not cause bandwidth change after frequency trimming, thereby ensuring that the bandwidth of the filter is consistent between batches during production.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a filter and its frequency correction method. Background Technology

[0002] To ensure high-quality data communication across spectrums, smartphones need at least 50 filters to support the ever-increasing number of frequency bands. However, this dense band density exacerbates uplink interference issues within the system. Furthermore, with continuous upgrades in communication technology and the deployment of new technologies such as carrier aggregation and multiple-input multiple-output (MIMO), the number of communication frequency bands will continue to increase dramatically.

[0003] With the rapid development of communication technology, the deployment of various new technologies has also posed new challenges to the performance of filters. This requires filters to meet requirements such as low insertion loss, large bandwidth, high rectangularity, and high isolation.

[0004] The biggest challenge in filter fabrication is the susceptibility of frequency deviation. Current technology employs frequency correction equipment to correct the filter's frequency. There are currently two main frequency correction methods:

[0005] The first method involves surface oxidation of the interdigital transducer with oxygen to induce a low-frequency bias. The main principle of this method is to oxidize the interdigital surface, thereby creating a mass loading effect and a change in the stiffness of the interdigital structure. Because the left and right skirts of the filter passband have different sensitivities to oxygen correction, a certain degree of bandwidth variation will occur during correction.

[0006] The second method involves etching the silicon dioxide passivation layer covering the surface to adjust the frequency, thereby increasing the filter's frequency. This method involves varying the thickness of the silicon dioxide layer, which can cause bandwidth differences due to surface acoustic wave coupling.

[0007] In summary, existing methods for frequency correction of filters can cause bandwidth variations, which can lead to inconsistent bandwidth between batches of filters during production. Summary of the Invention

[0008] To address the shortcomings of the existing technologies, this invention proposes a new filter and its frequency correction method to solve the problem that existing frequency correction methods for filters cause bandwidth variations, resulting in inconsistent bandwidth between batches during filter production.

[0009] To address the aforementioned technical problems, in a first aspect, the present invention provides a filter frequency correction method, which includes the following steps:

[0010] Step S1: Deposit silicon dioxide on the surface of the wafer with the filter pattern to form a frequency correction layer; the thickness of the frequency correction layer is less than or equal to 100 nm.

[0011] Step S2: Perform a first probe test on the wafer with the frequency correction layer formed on its surface to obtain the first test data; the first test data includes the first measured left frequency of the filter on the wafer;

[0012] Step S3: Based on the difference between the target left frequency of the target data and the first measured left frequency, the frequency correction layer is thinned to complete the first frequency correction; the target data includes the target left frequency and the target right frequency of the target filter; the first frequency correction aligns the left frequency of the filter on the wafer with the target left frequency;

[0013] Step S4: Perform a second probe test on the wafer after the first frequency correction to obtain second test data; the probe position on the wafer during the second probe test is the same as the probe position on the wafer during the first probe test; the second test data includes the second measured left frequency and the second measured right frequency of the filter on the wafer after the first frequency correction.

[0014] Step S5: After aligning the second measured left-hand frequency with the target left-hand frequency, the wafer after the first frequency correction is sequentially subjected to photoresist coating, exposure, and development, so that the surface of the parallel resonator of the filter on the wafer after the first frequency correction is completely covered by photoresist; the photoresist coating is the process of coating photoresist onto the surface of the wafer after the first frequency correction.

[0015] Step S6: Curing the photoresist covering the surface of the parallel resonator, and according to the difference between the target right frequency and the second measured right frequency, thinning the frequency correction layer in the region corresponding to the series resonator of the filter on the wafer after the first frequency correction to complete the second frequency correction; the second frequency correction makes the right frequency of the filter on the wafer aligned with the target right frequency.

[0016] Step S7: After aligning the right-side frequency of the filter on the wafer after the second frequency correction with the target right-side frequency, peel off the photoresist covering the surface of the parallel resonator on the wafer after the second frequency correction.

[0017] Preferably, the target data further includes the target bandwidth of the target filter;

[0018] The filter frequency correction method further includes the following steps after step S7;

[0019] Step S8: Clean the wafer surface after removing the photoresist, and then perform a third probe test to obtain the third test data; the probe position on the wafer during the third probe test is the same as the probe position on the wafer during the first probe test, and the third test data includes the bandwidth of the filter on the wafer after removing the photoresist.

[0020] Determine whether the bandwidth of the filter on the wafer after photoresist removal is the same as the target bandwidth:

[0021] If they are the same, the frequency correction of the filter is complete.

[0022] Preferably, after step S4, the following steps are further included:

[0023] Step S41: Check whether the second measured left frequency is aligned with the target left frequency.

[0024] If they are different, repeat steps S1-S3 on the wafer after the first frequency correction until the second measured left frequency is aligned with the target left frequency.

[0025] Preferably, after step S6, the following steps are further included:

[0026] Step S61: Perform a fourth probe test on the wafer after the second frequency correction to obtain fourth test data; the probe position on the wafer during the fourth probe test is the same as the probe position on the wafer during the first probe test, and the fourth test data includes the third measured right frequency of the filter on the wafer after the second frequency correction.

[0027] Step S62: Check whether the third measured right frequency is aligned with the target right frequency.

[0028] If they are different, repeat step S6 on the wafer after the second frequency correction until the third measured right frequency is aligned with the target right frequency.

[0029] Preferably, both the first frequency correction and the second frequency correction are performed using reactive ion etching or wet etching methods.

[0030] Preferably, in step S5, the photoresist covers the edge of the parallel resonator by more than 3 μm.

[0031] Preferably, in step S7, the photoresist is stripped using a dry etching method or a wet etching method.

[0032] Preferably, in step S3, the thickness of the frequency correction layer after the first frequency correction is greater than 3 nm.

[0033] Secondly, the present invention provides a filter frequency correction method, which includes the following steps:

[0034] Step S1: Perform a first probe test on the wafer with the filter pattern to obtain the first test data; the first test data includes the first measured right frequency of the filter on the wafer;

[0035] Step S2: Based on the difference between the target right frequency of the target data and the first measured right frequency, the wafer is oxidized and thinned to complete the first frequency correction; the target data includes the target left frequency and the target right frequency of the target filter; the first frequency correction aligns the right frequency of the filter on the wafer with the target left frequency;

[0036] Step S3: Perform a second probe test on the wafer after the first frequency correction to obtain second test data; the probe position on the wafer during the second probe test is the same as the probe position on the wafer during the first probe test; the second test data includes the second measured left frequency and the second measured right frequency of the filter on the wafer after the first frequency correction.

[0037] Step S4: After aligning the second measured right-hand frequency with the target right-hand frequency, the wafer after the first frequency correction is sequentially subjected to photoresist coating, exposure, and development, so that the surface of the series resonator of the filter on the wafer after the first frequency correction is completely covered by photoresist; the photoresist coating is the process of coating photoresist onto the surface of the wafer after the first frequency correction.

[0038] Step S5: Curing the photoresist covering the surface of the series resonator, and according to the difference between the target left frequency and the second measured left frequency, oxidizing and thinning the wafer corresponding to the parallel resonator of the filter on the wafer after the first frequency correction to complete the second frequency correction; the second frequency correction makes the left frequency of the filter on the wafer aligned with the target left frequency.

[0039] Step S6: After aligning the left-side frequency of the filter on the wafer after the second frequency correction with the target left-side frequency, peel off the photoresist covering the surface of the series resonator on the wafer after the second frequency correction.

[0040] Thirdly, the present invention provides a filter that is obtained by frequency correction using the above-described filter correction method.

[0041] Compared with the prior art, the filter frequency correction method of the present invention first coats the parallel resonators of the filter on the wafer after the first frequency correction with photoresist for protection before the second frequency correction, and then performs a second frequency correction on the correction layer corresponding to the area of ​​the series resonator of the filter on the wafer that is not coated with photoresist. In this way, the bandwidth of the filter can be adjusted by the second frequency correction, so that the bandwidth of the filter will not change after the frequency correction, thereby ensuring that the bandwidth of the filter is consistent between batches during production. Attached Figure Description

[0042] The present invention will now be described in detail with reference to the accompanying drawings. The above and other aspects of the present invention will become clearer and more readily understood through the detailed description following the accompanying drawings. In the drawings:

[0043] Figure 1 This is a flowchart of the filter frequency correction method provided in Embodiment 1 of the present invention;

[0044] Figure 2 A comparison diagram of the frequency waveforms of the pre-correction filter and the target filter provided for the prior art; wherein, (a) is the frequency waveform diagram of the pre-correction filter, and (b) is a comparison diagram of the frequency waveforms of the pre-correction filter and the target filter.

[0045] Figure 3 The above is a comparison diagram of the frequency waveforms of the filter to be processed and the target filter provided in Embodiment 1 of the present invention; wherein, (c) is the frequency waveform diagram of the filter to be processed, and (d) is the frequency waveform diagram of the target filter;

[0046] Figure 4 The above is a comparison diagram of the frequency waveforms of the filter before the first frequency correction and the target filter provided in Embodiment 1 of the present invention; wherein, (e) is the frequency waveform diagram of the filter before the first frequency correction, and (f) is a comparison diagram of the frequency waveforms of the filter before the first frequency correction and the target filter.

[0047] Figure 5 The above is a comparison diagram of the frequency waveforms of the filter before the second frequency correction and the target filter provided in Embodiment 1 of the present invention; wherein, (g) is a frequency waveform diagram of the filter before the second frequency correction, and (h) is a comparison diagram of the frequency waveforms of the filter before the second frequency correction, the target filter, and the filter after the frequency correction is completed.

[0048] Figure 6 The image shows a comparison of the photoresist coverage for the first and second frequency correction of the filter provided in Embodiment 1 of the present invention; wherein, (i) is the photoresist coverage image for the first frequency correction of the filter, and (j) is the photoresist coverage image for the second frequency correction of the filter;

[0049] Figure 7The flowchart illustrates the steps of the filter frequency correction method provided in Embodiment 2 of the present invention. Detailed Implementation

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application, are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0051] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0052] 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, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] Example 1

[0054] This invention provides a filter frequency correction method, combined with Figure 1 As shown, it includes the following steps:

[0055] S1. A frequency correction layer is formed by depositing silicon dioxide on the surface of a wafer with a filter pattern.

[0056] The thickness of the frequency correction layer is less than or equal to 100 nm; the frequency correction layer formed by silicon dioxide deposition can also serve as a protective layer.

[0057] S2. Perform the first probe test on the wafer with the frequency correction layer formed on the surface to obtain the first test data.

[0058] The first test data includes at least the first measured left frequency of the filter on the wafer, and may also include the first measured right frequency, the first measured center frequency, and the first measured bandwidth of the filter on the wafer. The center frequency of the filter is half the sum of the left and right frequencies, and the bandwidth of the filter is the left frequency minus the right frequency.

[0059] A comparison of the frequency waveforms of the pre-correction filter and the target filter in the existing technology is shown in the figure below. Figure 2 As shown, (a) is the frequency waveform of the filter before frequency correction in the prior art, and (b) is a comparison diagram of the frequency waveforms of the filter before frequency correction and the target filter in the prior art. The gray line represents the frequency waveform of the filter before frequency correction in the prior art, and the black dashed line represents the frequency waveform of the target filter, i.e., the frequency waveform of the filter after frequency correction. The comparison shows that the frequency waveform of the target filter is different from the frequency waveform of the filter to be processed. The comparison diagram of the frequency waveforms of the filter to be processed and the target filter in this embodiment is shown below. Figure 3 As shown, (c) is the frequency waveform of the filter to be processed, and (d) is the frequency waveform of the target frequency, that is, the frequency waveform of the filter after frequency correction. It can be seen from the comparison that the frequency waveform of the target frequency is different from the frequency waveform of the filter to be processed.

[0060] S3. Based on the difference between the target left frequency of the target data and the first measured left frequency, the frequency correction layer is thinned to complete the first frequency correction.

[0061] The target data includes the target left frequency and the target right frequency of the target filter; the purpose of the first frequency correction is to align the left frequency of the filter on the wafer with the target left frequency.

[0062] During the first frequency correction, it is not necessary to coat the wafer with photoresist. The degree of the first frequency correction is determined by the difference between the target left frequency in the target data and the first measured left frequency. However, it is necessary to ensure that the thickness of the frequency correction layer is greater than 3nm after the first frequency correction in order to align the left frequency of the filter on the wafer with the target left frequency, while ensuring the functional stability of silicon dioxide as the frequency correction layer or passivation layer.

[0063] S4. Perform a second probe test on the wafer after the first frequency correction to obtain the second test data.

[0064] The second test data includes the second measured left frequency and the second measured right frequency of the filter on the wafer after the first frequency correction.

[0065] The probe placement on the wafer during the second probe test is the same as that during the first probe test. This design allows for in-situ observation, enabling a better determination of whether the second measured left-side frequency is the same as the target left-side frequency, i.e., consistency.

[0066] After step S4, the following steps are also included:

[0067] Step S41: Check whether the second measured left frequency is aligned with the target left frequency.

[0068] If they are different, repeat steps S1-S3 on the wafer after the first frequency correction until the second measured left frequency is aligned with the target left frequency.

[0069] In this embodiment, the frequency waveform comparison diagram between the filter before the first frequency correction and the target filter is shown below. Figure 4 As shown, (e) is the frequency waveform of the filter before the first frequency correction, and (f) is a comparison diagram of the frequency waveform of the filter before the first frequency correction and the frequency waveform of the target filter. In this diagram, the gray line is the frequency waveform of the filter before the first frequency correction, and the black dashed line is the frequency waveform of the target filter, that is, the frequency waveform of the filter after the first frequency correction. By comparison, it can be seen that the frequency waveform of the filter before the first frequency correction and the frequency waveform of the filter after the first frequency correction are different.

[0070] S5. After the second measured left frequency is aligned with the target left frequency, the wafer after the first frequency correction is sequentially subjected to homogenization, exposure and development.

[0071] The spin coating process involves applying photoresist to the surface of the wafer after the first frequency correction. The spin coating is performed using a spin coater with the following operating parameters: rotation speed of 3500 rpm, temperature of 35°C, and time of 120 seconds. Of course, the operating parameters of the spin coater can be adapted to meet actual needs, as long as the photoresist is applied to the surface of the wafer.

[0072] The spin coating, exposure, and development processes ensure that the surface of the parallel resonator of the filter on the wafer after the first frequency correction is completely covered by photoresist.

[0073] The photoresist coating covers the edges of the parallel resonator by more than 3 μm. This design ensures that subsequent processes do not affect the performance of the parallel resonator.

[0074] S6. The photoresist covering the surface of the parallel resonator is cured, and the frequency correction layer in the region corresponding to the series resonator of the filter on the wafer after the first frequency correction is thinned according to the difference between the target right frequency and the second measured right frequency to complete the second frequency correction.

[0075] The purpose of the second frequency correction is to align the right-hand frequency of the filter on the wafer with the target right-hand frequency.

[0076] The degree of the second frequency correction is determined by the difference between the right-hand frequency of the target and the second measured right-hand frequency.

[0077] Both the second frequency correction and the first frequency correction are performed using reactive ion etching or wet etching methods; and frequency correction involves thinning the corresponding positions so that the thinned positions are aligned with the positions of the target filter or the required filter.

[0078] After step S6, the following steps are also included:

[0079] Step S61: Perform a fourth probe test on the wafer after the second frequency correction to obtain fourth test data; the probe position on the wafer during the fourth probe test is the same as the probe position on the wafer during the first probe test, and the fourth test data includes the third measured right frequency of the filter on the wafer after the second frequency correction.

[0080] Step S62: Check whether the third measured right frequency is aligned with the target right frequency.

[0081] If they are different, repeat step S6 on the wafer after the second frequency correction until the third measured right frequency is aligned with the target right frequency.

[0082] In this embodiment, the frequency waveform comparison between the filter before the second frequency correction and the target filter is shown in the figure below. Figure 5 As shown, (g) is the frequency waveform of the filter before the second frequency correction, and (h) is a comparison diagram of the frequency waveform of the filter before the second frequency correction, the frequency waveform of the target filter, and the frequency waveform of the filter after the frequency correction. The narrower gray line represents the frequency waveform of the filter before the second frequency correction, the black dashed line represents the frequency waveform of the target filter (i.e., the required frequency waveform of the filter after the second frequency correction), and the wider gray line represents the frequency waveform of the filter after the second frequency correction. The comparison shows that the frequency waveforms of the filter before and after the second frequency correction are different. In this embodiment, the photoresist coverage comparison diagrams for the first and second frequency corrections of the filter are shown below. Figure 6 As shown, the series resonators of the on-wafer filter are connected between the signal input terminal In and the signal output terminal Out, and are resonators Rs1, Rs2, and Rs3 respectively; the parallel resonators of the on-wafer filter are grounded to Gnd, and are resonators Rp1 and Rp2 respectively.

[0083] S7. After aligning the right-hand frequency of the filter on the wafer after the second frequency correction with the target right-hand frequency, peel off the photoresist covering the surface of the parallel resonator on the wafer after the second frequency correction.

[0084] The photoresist is stripped using either a dry etching method or a wet etching method.

[0085] Following step S7, the following steps are also included:

[0086] S8. Clean the wafer surface after stripping the photoresist, and then perform a third probe test to obtain the third test data.

[0087] The third probe test uses the same pinning position on the wafer as the first probe test, and the third test data includes the bandwidth of the filter on the wafer after the photoresist is removed.

[0088] Determine whether the bandwidth of the filter on the wafer after photoresist removal is the same as the target bandwidth:

[0089] If they are the same, the frequency correction of the filter is complete.

[0090] If they are different, the filter is determined to be defective or does not meet the requirements.

[0091] The third test data also includes the center frequency of the filter on the wafer after the photoresist is removed. Correspondingly, it can also be determined whether the center frequency of the filter on the wafer in the third test data is the same as the center frequency of the target filter, so as to improve the accuracy of the judgment.

[0092] The filter correction method in this embodiment takes the deposition of silicon dioxide as the correction layer (SiO2) as an example.

[0093] Compared with the prior art, the filter frequency correction method in this embodiment protects the parallel resonators of the filter on the wafer after the first frequency correction by coating them with photoresist before the second frequency correction. Then, the frequency correction layer corresponding to the area of ​​the series resonator of the filter on the wafer that is not coated with photoresist is subjected to the second frequency correction. In this way, the bandwidth of the filter can be adjusted by the second frequency correction, so that the bandwidth of the filter will not change after the frequency correction, thereby ensuring that the bandwidth of the filter is consistent between batches during production.

[0094] Example 2

[0095] This invention provides a filter frequency correction method, combined with Figure 7 As shown, it includes the following steps:

[0096] S11. Perform the first probe test on the wafer with the filter pattern to obtain the first test data.

[0097] The first test data includes the first measured right-hand frequency of the filter on the wafer.

[0098] S12. Based on the difference between the target right-hand frequency of the target data and the first measured right-hand frequency, the wafer is oxidized and thinned to complete the first frequency correction.

[0099] The target data includes the target left frequency and the target right frequency of the target filter; the first frequency correction aligns the right frequency of the filter on the wafer with the target left frequency.

[0100] S13. Perform a second probe test on the wafer after the first frequency correction to obtain the second test data.

[0101] In the second probe test, the pinning position on the wafer is the same as that in the first probe test. The second test data includes the second measured left frequency and the second measured right frequency of the filter on the wafer after the first frequency correction.

[0102] S14. After the second measured right frequency is aligned with the target right frequency, the wafer after the first frequency correction is sequentially subjected to homogenization, exposure and development.

[0103] The process of spin coating involves applying photoresist to the surface of the wafer after the first frequency correction; the spin coating, the exposure, and the development process ensure that the surface of the series resonator of the filter on the wafer after the first frequency correction is completely covered by photoresist.

[0104] S15. The photoresist covering the surface of the series resonator is cured, and according to the difference between the target left frequency and the second measured left frequency, the wafer corresponding to the region of the parallel resonator of the filter on the wafer after the first frequency correction is oxidized and thinned to complete the second frequency correction.

[0105] The second frequency correction aligns the left-hand frequency of the filter on the wafer with the target left-hand frequency.

[0106] S16. After aligning the left-side frequency of the filter on the wafer after the second frequency correction with the target left-side frequency, peel off the photoresist covering the surface of the series resonator on the wafer after the second frequency correction.

[0107] Following step S16, the following steps are also included:

[0108] S17. Clean the wafer surface after stripping the photoresist, and then perform a third probe test to obtain the third test data.

[0109] Determine whether the bandwidth of the filter on the wafer after photoresist removal is the same as the target bandwidth:

[0110] If they are the same, the frequency correction of the filter is complete.

[0111] If they are different, the filter is determined to be defective or does not meet the requirements.

[0112] The filter frequency correction method in this embodiment uses oxygen (O2) to oxidize and thin the surface of the interdigital transducer to complete the frequency correction. That is, the first and second frequency corrections in this embodiment are completed by oxidation and thinning. Therefore, the filter frequency correction method in this embodiment does not need to deposit silicon dioxide before frequency correction, but deposits silicon dioxide as a protective layer after frequency correction is completed.

[0113] Since this embodiment uses oxidation thinning to complete the frequency correction, the difference from the above embodiment is that this embodiment first performs the first frequency correction on the right side of the filter on the wafer, then protects the series resonator on the right side of the filter on the wafer with photoresist, and finally performs the second frequency correction on the parallel resonator on the left side of the filter on the wafer that is not protected by photoresist. The probe testing and judgment steps are also basically the same. Therefore, the basic principle of the filter frequency correction method in this embodiment is the same as or similar to the basic principle of the filter frequency correction method in Embodiment 1, and it can also achieve the technical effect achieved by the filter frequency correction method in Embodiment 1, which will not be elaborated here.

[0114] Example 3

[0115] This embodiment provides a filter, which is obtained by frequency correction using the filter correction method of Embodiment 1 or Embodiment 2.

[0116] Since the filter in this embodiment is obtained by frequency correction using the filter frequency correction method of Embodiment 1 or Embodiment 2, it can also achieve the technical effect achieved by the filter frequency correction method in Embodiment 1 or Embodiment 2, and will not be described in detail here.

[0117] It should be noted that the various embodiments described above with reference to the accompanying drawings are merely illustrative of the present invention and not intended to limit its scope. Those skilled in the art should understand that any modifications or equivalent substitutions made to the present invention without departing from its spirit and scope should be included within the scope of the present invention. Furthermore, unless the context otherwise requires, words appearing in the singular include those in the plural, and vice versa. Additionally, unless specifically stated otherwise, all or part of any embodiment may be used in conjunction with all or part of any other embodiment.

Claims

1. A filter frequency correction method, characterized in that, The filter frequency correction method includes the following steps: Step S1: Deposit silicon dioxide on the surface of the wafer with the filter pattern to form a frequency correction layer; the thickness of the frequency correction layer is less than or equal to 100 nm. Step S2: Perform a first probe test on the wafer with the frequency correction layer formed on its surface to obtain the first test data; the first test data includes the first measured left frequency of the filter on the wafer; Step S3: Based on the difference between the target left frequency of the target data and the first measured left frequency, the frequency correction layer is thinned to complete the first frequency correction; the target data includes the target left frequency and the target right frequency of the target filter; the first frequency correction aligns the left frequency of the filter on the wafer with the target left frequency; Step S4: Perform a second probe test on the wafer after the first frequency correction to obtain second test data; the probe position on the wafer during the second probe test is the same as the probe position on the wafer during the first probe test; the second test data includes the second measured left frequency and the second measured right frequency of the filter on the wafer after the first frequency correction. Step S5: After aligning the second measured left-hand frequency with the target left-hand frequency, the wafer after the first frequency correction is sequentially subjected to photoresist coating, exposure, and development, so that the surface of the parallel resonator of the filter on the wafer after the first frequency correction is completely covered by photoresist; the photoresist coating is the process of coating photoresist onto the surface of the wafer after the first frequency correction. Step S6: Curing the photoresist covering the surface of the parallel resonator, and according to the difference between the target right frequency and the second measured right frequency, thinning the frequency correction layer in the region corresponding to the series resonator of the filter on the wafer after the first frequency correction to complete the second frequency correction; the second frequency correction makes the right frequency of the filter on the wafer aligned with the target right frequency. Step S7: After aligning the right-side frequency of the filter on the wafer after the second frequency correction with the target right-side frequency, peel off the photoresist covering the surface of the parallel resonator on the wafer after the second frequency correction.

2. The filter frequency correction method as described in claim 1, characterized in that, The target data also includes the target bandwidth of the target filter; In the filter frequency correction method, after step S7, there is also Includes the following steps; Step S8: Clean the wafer surface after removing the photoresist, and then perform a third probe test to obtain the third test data; the probe position on the wafer during the third probe test is the same as the probe position on the wafer during the first probe test, and the third test data includes the bandwidth of the filter on the wafer after removing the photoresist. Determine whether the bandwidth of the filter on the wafer after photoresist removal is the same as the target bandwidth: If they are the same, the frequency correction of the filter is complete.

3. The filter frequency correction method as described in claim 1, characterized in that, After step S4, the following steps are also included: Step S41: Check whether the second measured left frequency is aligned with the target left frequency. If they are different, repeat steps S1-S3 on the wafer after the first frequency correction until the second measured left frequency is aligned with the target left frequency.

4. The filter frequency correction method as described in claim 1, characterized in that, After step S6, the following steps are also included: Step S61: Perform a fourth probe test on the wafer after the second frequency correction to obtain fourth test data; the probe position on the wafer during the fourth probe test is the same as the probe position on the wafer during the first probe test, and the fourth test data includes the third measured right frequency of the filter on the wafer after the second frequency correction. Step S62: Check whether the third measured right frequency is aligned with the target right frequency. If they are different, repeat step S6 on the wafer after the second frequency correction until the third measured right frequency is aligned with the target right frequency.

5. The filter frequency correction method as described in claim 1, characterized in that, Both the first and second frequency corrections are performed using reactive ion etching or wet etching methods.

6. The filter frequency correction method as described in claim 1, characterized in that, In step S5, the photoresist covers the edge of the parallel resonator by more than 3 μm.

7. The filter frequency correction method as described in claim 1, characterized in that, In step S7, the photoresist is stripped using a dry etching method or a wet etching method.

8. The filter frequency correction method as described in claim 1, characterized in that, In step S3, the thickness of the frequency correction layer after the first frequency correction is greater than 3nm.

9. A filter frequency correction method, characterized in that, The filter frequency correction method includes the following steps: Step S1: Perform a first probe test on the wafer with the filter pattern to obtain the first test data; the first test data includes the first measured right frequency of the filter on the wafer; Step S2: Based on the difference between the target right frequency of the target data and the first measured right frequency, the wafer is oxidized and thinned to complete the first frequency correction; the target data includes the target left frequency and the target right frequency of the target filter; the first frequency correction aligns the right frequency of the filter on the wafer with the target left frequency; Step S3: Perform a second probe test on the wafer after the first frequency correction to obtain second test data; the probe position on the wafer during the second probe test is the same as the probe position on the wafer during the first probe test; the second test data includes the second measured left frequency and the second measured right frequency of the filter on the wafer after the first frequency correction. Step S4: After aligning the second measured right-hand frequency with the target right-hand frequency, the wafer after the first frequency correction is sequentially subjected to photoresist coating, exposure, and development, so that the surface of the series resonator of the filter on the wafer after the first frequency correction is completely covered by photoresist; the photoresist coating is the process of coating photoresist onto the surface of the wafer after the first frequency correction. Step S5: Curing the photoresist covering the surface of the series resonator, and according to the difference between the target left frequency and the second measured left frequency, oxidizing and thinning the wafer corresponding to the parallel resonator of the filter on the wafer after the first frequency correction to complete the second frequency correction; the second frequency correction makes the left frequency of the filter on the wafer aligned with the target left frequency. Step S6: After aligning the left-side frequency of the filter on the wafer after the second frequency correction with the target left-side frequency, peel off the photoresist covering the surface of the series resonator on the wafer after the second frequency correction.

10. A filter, characterized in that, The filter is obtained by frequency correction using the filter correction method according to any one of claims 1 to 9.

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