Surface acoustic wave resonator and method for manufacturing the same

Abstract

The application discloses a surface acoustic wave resonator and a manufacturing method thereof. The surface acoustic wave resonator comprises a piezoelectric substrate with an electrode, and a first dielectric layer arranged on a surface layer portion of the electrode; the surface layer portion of the electrode is an oxide of the electrode material, and has a thickness of 5-75 nm, and can perform first trimming on a resonant frequency of the surface acoustic wave resonator; the sound velocity of the first dielectric layer is 84 Å / ps-90 Å / ps, and can perform second trimming on the resonant frequency of the surface acoustic wave on the basis of the first trimming, so as to trim the resonant frequency of the surface acoustic wave resonator to a target resonant frequency or closer to the target resonant frequency. The surface acoustic wave resonator can reduce the trimming amount of the first trimming based on the synergistic effect of the first dielectric layer and the surface layer portion of the electrode, can avoid the phenomenon that the conductivity of the electrode does not meet the device requirement due to the over-thickness of the surface layer portion, and thus can improve the resonant frequency trimming accuracy while ensuring the reliability of the device.

Description

Technical Field

[0001] The embodiments in this application relate to the field of resonator technology, specifically to surface acoustic wave resonators and their manufacturing methods. Background Technology

[0002] To correct the resonant frequency of a surface acoustic wave (SAW) resonator to the target resonant frequency, a dielectric layer with frequency modulation function is usually placed above the electrode layer. This protects the device while influencing the propagation characteristics of the SAW, thereby achieving the purpose of correcting the resonant frequency.

[0003] A common method for correcting the resonant frequency in surface acoustic wave (SAW) resonators is to coat the electrode surface with a silicon dioxide layer, serving as both a device protection layer and a frequency correction layer, and then adjust the thickness of this silicon dioxide layer. However, this method has significant limitations: the accuracy of the resonant frequency correction is highly sensitive to changes in the thickness of the silicon dioxide layer, and the selection of this thickness must also consider the protection requirements of the device. This resonant frequency correction method, which needs to consider multiple objectives, presents a challenge in maintaining the overall reliability of the device while achieving accurate resonant frequency correction.

[0004] Therefore, how to achieve precise adjustment of the resonant frequency in the structure of a surface acoustic wave (SAW) resonator while ensuring the reliability of the device remains a technical problem that urgently needs to be solved in the design of SAW resonators. Summary of the Invention

[0005] In view of this, this application provides a surface acoustic wave resonator with accurate resonant frequency and high reliability, and a method for manufacturing the same.

[0006] In a first aspect, embodiments of this application provide a surface acoustic wave resonator, comprising: piezoelectric substrate; An electrode is disposed on the piezoelectric substrate, the surface portion of the electrode is an oxide of the electrode material, and the thickness of the surface portion is 5 nm to 75 nm. A first dielectric layer is disposed on the surface portion, and the sound velocity is 84 Å / ps to 90 Å / ps.

[0007] In some embodiments, the sound velocity of the first dielectric layer is 84 Å / ps to 87 Å / ps; and or, the thickness of the first dielectric layer is 15 nm to 45 nm.

[0008] In some embodiments, the first dielectric layer is a silicon nitride layer with a thickness of 20 nm to 45 nm and / or a sound density of 84 Å / ps to 86 Å / ps.

[0009] In some embodiments, the ratio between the thickness of the surface portion and the thickness of the electrode ranges from 5% to 15%.

[0010] In some embodiments, the oxide is aluminum oxide, and the thickness of the surface layer is 10 nm to 60 nm.

[0011] In some embodiments, the surface layer is used to generate a first frequency offset to reduce the initial resonant frequency of the surface acoustic wave resonator to a first resonant frequency, and the first dielectric layer is used to generate a second frequency offset to compensate for the difference between the first resonant frequency and the target resonant frequency.

[0012] In some embodiments, a second dielectric layer is further included, disposed on the first dielectric layer, and the sound velocity is less than 40 Å / ps.

[0013] In some embodiments, the second dielectric layer is a silicon dioxide layer.

[0014] In some embodiments, the surface portion causes the rate of increase in resistance of the electrode to be less than or equal to 10%.

[0015] Secondly, some embodiments of this application provide a method for manufacturing a surface acoustic wave resonator as described in any one of the first aspects, comprising: An initial structure is provided, the initial structure comprising a piezoelectric substrate and electrodes formed on the piezoelectric substrate; The surface portion of the electrode is subjected to oxidative modification, and the thickness of the surface portion ranges from 5 to 75 nm. A first dielectric layer is deposited on the surface portion, the first dielectric layer having a sound velocity of 84 Å / ps to 90 Å / ps.

[0016] In some embodiments, depositing the first dielectric layer on the surface portion includes: Obtain the first resonant frequency of the surface acoustic wave resonator after the oxidation modification. Based on the first difference between the first resonant frequency and the target resonant frequency, and the correspondence between the sound velocity of the first dielectric layer and the frequency conversion amount, the target sound velocity of the first dielectric layer is determined in the range of 84 Å / ps to 90 Å / ps, such that after the formation of the first dielectric layer, the surface acoustic wave resonator has a second resonant frequency, and the second difference between the second resonant frequency and the target resonant frequency is less than the first difference. Based on the target sound velocity, determine the deposition process parameters for depositing the first medium layer; The first dielectric layer is deposited on the surface portion according to the deposition process parameters.

[0017] In some embodiments, depositing the first dielectric layer on the surface portion further includes: Based on the first difference and the correspondence between the thickness of the first dielectric layer and the frequency conversion amount, the target thickness of the first dielectric layer is determined within the range of 15nm to 45nm. The step of determining the deposition process parameters for depositing the first dielectric layer based on the target sound velocity includes: The deposition process parameters are determined based on the target sound velocity and target thickness of the first dielectric layer.

[0018] In some embodiments, the first dielectric layer is a silicon nitride layer, and the deposition process parameters include at least one of the following: silane to ammonia flow ratio, radio frequency power, and deposition temperature.

[0019] In some embodiments, when the second difference is greater than zero, the manufacturing method further includes: A second dielectric layer with a sound velocity range of less than 40 Å / ps is deposited on the surface of the first dielectric layer.

[0020] In some embodiments, prior to the oxidative modification of the surface portion of the electrode, the method further includes: The resonant frequency of the initial structure is obtained as the initial frequency of the surface acoustic wave resonator. The processing strategy for the initial structure is determined based on the deviation between the initial resonant frequency and the target resonant frequency, and the maximum value of the oxidation adjustment amount; wherein, when the deviation is greater than zero and the absolute value of the deviation is greater than the maximum value, the processing strategy is a high-frequency offset correction strategy; wherein, the oxidation adjustment amount is the frequency offset between the first resonant frequency of the surface acoustic wave resonator after the oxidation modification and the initial resonant frequency; the maximum value is determined based on the constraint that the oxidation modification causes the resistance increase rate of the electrode to be less than or equal to 10%. The oxidation modification of the surface portion of the electrode includes: When the processing strategy is the high-frequency bias processing strategy, the surface layer of the electrode is oxidized and modified.

[0021] The surface acoustic wave (SAW) resonator provided in this embodiment addresses the problem of difficulty in balancing resonant frequency correction accuracy and device reliability when using a silicon dioxide layer as a protective layer for resonant frequency correction. By setting the surface portion of the electrodes on the piezoelectric substrate as an oxide of the electrode material with a thickness of 5 to 75 nm, a first adjustment of the SAW resonator's resonant frequency can be performed, bringing the resonant frequency closer to the target resonant frequency. Furthermore, by setting a first dielectric layer with a sound velocity of 84 Å / ps to 90 Å / ps on this surface portion, a second adjustment of the SAW resonant frequency can be performed based on the first adjustment. This, in conjunction with the surface portion of the electrodes, adjusts the SAW resonator's resonant frequency to the target resonant frequency or closer to it. This reduces the adjustment amount of the first adjustment, thus avoiding the phenomenon where the electrode conductivity does not meet device requirements due to an excessively thick surface portion. Therefore, while improving the accuracy of resonant frequency correction, device reliability is ensured. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of a surface acoustic wave resonator provided according to some embodiments of this application.

[0024] Figure 2 This is a schematic diagram of the structure of a surface acoustic wave resonator provided according to other embodiments of this application.

[0025] Figure 3 This is a schematic diagram of the manufacturing process of a surface acoustic wave resonator provided in some embodiments of this application.

[0026] Figure 4 This is a schematic diagram of the initial structure of the surface acoustic wave resonator provided in the embodiments of this application.

[0027] Figure 5 This is a schematic diagram of the oxide trimming structure of the surface acoustic wave resonator provided in the embodiments of this application.

[0028] Figure 6 This is a schematic diagram showing the relationship between the sound velocity and frequency conversion of a silicon nitride layer.

[0029] Figure 7 This is a schematic diagram showing the relationship between the thickness of the silicon nitride layer and the frequency conversion amount.

[0030] Figure 8 This is a schematic diagram of the steps for depositing a first dielectric layer in the manufacturing method provided according to the embodiments of this application.

[0031] Figure 9 This is a schematic diagram of the closed-loop process flow of the manufacturing method provided according to the embodiments of this application.

[0032] Figure label: Surface acoustic wave resonator 100, initial structure 101, oxide trimming structure 102, piezoelectric substrate 1, electrode 2, surface layer 3, first dielectric layer 4, second dielectric layer 5. Detailed Implementation

[0033] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0034] After the initial structure of the surface acoustic wave (SAW) resonator (a piezoelectric substrate with electrodes) is formed, it is necessary to take certain measures to correct its resonant frequency in order to accurately correct the resonant frequency to the target resonant frequency. A commonly used method in related technologies for resonant frequency correction is to utilize the silicon dioxide layer covering the electrodes, which, while serving as a protective layer for the device, can also be used as a resonant frequency correction layer based on its ability to alter the speed of SAW. By adjusting the thickness of the silicon dioxide layer, a certain frequency offset is achieved to correct the resonant frequency to the target resonant frequency. Specifically, the basic working principle of this resonant frequency correction method in related technologies is that the SAW propagation speed of the silicon dioxide layer is usually lower than that of the electrodes and the piezoelectric substrate. Increasing its thickness reduces the overall effective sound speed, thereby lowering the resonant frequency. By precisely controlling the thickness of the silicon dioxide layer, the resonant frequency can be corrected towards the target resonant frequency.

[0035] However, this resonant frequency correction method in related technologies struggles to ensure device reliability when pursuing high resonant frequency correction accuracy. The main reason is that the silicon dioxide layer simultaneously serves the dual functions of resonant frequency correction and mechanical environmental protection. Achieving precise resonant frequency correction requires extremely stringent control over the thickness of the silicon dioxide layer. Furthermore, as the final physical protective barrier for the device, the thickness of the silicon dioxide layer itself needs to be designed within a range sufficient to guarantee mechanical strength and environmental isolation. These two thickness requirements are difficult to simultaneously meet. Specifically, even a slight adjustment in the thickness of the silicon dioxide layer can cause a significant frequency shift. If the thickness is too thin, it leads to insufficient protection for the device, affecting its reliability; if it is too thick, it easily causes resonant frequency overtuning, affecting the accuracy of resonant frequency correction and potentially degrading other device performance indicators (such as bandwidth and insertion loss). When using a silicon dioxide layer for resonant frequency correction, once overtuning occurs, because the silicon dioxide layer also serves a protective function, it is difficult to remedy the situation by simply thinning it later, potentially leading to direct performance degradation or device failure.

[0036] In related technologies, resonant frequency correction and device protection are both achieved through a single silicon dioxide layer. While this approach eliminates the need for additional functional layers to achieve frequency modulation, simplifying the structure of surface acoustic wave resonators, the thickness design of this silicon dioxide layer presents conflicting optimization objectives (resonant frequency correction and device protection). Any thickness adjustment aimed at optimizing one performance aspect may compromise the other. Therefore, relying on a single silicon dioxide layer to serve as both a device protection layer and a resonant frequency correction layer is insufficient to meet the demands for high resonant frequency correction accuracy and high device reliability.

[0037] Therefore, the inventors aimed to provide a resonant frequency offset resonator with a simple structure that balances frequency correction accuracy and device reliability during the research process. Based on this, the inventors provided an oxide-modified surface acoustic wave (SAW) resonator. This SAW resonator includes a piezoelectric substrate and electrodes disposed on the piezoelectric substrate. The surface layer of the electrodes is an oxide of the electrode material. This surface layer utilizes the higher density of the oxide compared to the electrode material to generate a mass loading effect, thereby achieving frequency modulation to the target resonant frequency. This oxide-modified SAW resonator achieves frequency modulation through electrode oxidation, eliminating the need for additional materials that can change the sound velocity to be deposited on the electrodes as a frequency modulation layer. Furthermore, the corresponding manufacturing process is compatible with conventional wafer fabrication processes, allowing accurate modulation to the target resonant frequency without additional photolithography steps, and without affecting the protective performance of the device's protective layer.

[0038] However, when the deviation between the initial resonant frequency and the target resonant frequency of the surface acoustic wave (SAW) resonator is large, relying solely on this oxide-based SAW resonator presents an irreconcilable contradiction. Specifically, the greater the deviation between the initial and target resonant frequencies, the thicker the aforementioned surface layer needs to be to generate a heavier mass load and achieve a greater frequency reduction. However, the greater the thickness of this surface layer, the greater the damage to the conductivity of the electrodes. A large deviation may cause the thickness of the surface layer to exceed the electrode damage safety threshold (beyond which the electrode's conductivity fails to meet device requirements, equivalent to electrode damage), thus deteriorating the electrode's conductivity. For example, in some high-frequency biased devices (where the positive deviation between the initial resonant frequency and the target resonant frequency is large), in order to tune the initial resonant frequency as close to the target resonant frequency as possible, the electrodes need to be deeply oxidized to obtain a thicker surface layer. This leads to a significant increase in the series resistance of the electrodes (the resistance formed by the series connection of the resistance of the unoxidized part and the resistance of the oxidized part), which in turn causes an increase in device insertion loss and a decrease in power tolerance. Ultimately, this results in an increase in the in-band attenuation of the filter containing the surface acoustic wave resonator and a decrease in the maximum input power it can withstand. Therefore, the surface acoustic wave resonator based on oxidation tuning provided by the inventors, while achieving relatively accurate resonant frequency tuning, is prone to damage to the conductivity of its electrodes. It still presents an irreconcilable contradiction between improving the resonant frequency accuracy and maintaining device performance, i.e., it is still difficult to simultaneously achieve accurate resonant frequency tuning and device reliability.

[0039] Through in-depth analysis of this oxide-modified surface acoustic wave (SAW) resonator, the inventors discovered that the root cause of the aforementioned irreconcilable contradiction lies in the fact that the resonant frequency modulation task is entirely undertaken by the surface layer of the electrodes, lacking other frequency modulation layers to cooperate in frequency modulation and prevent excessive electrode oxidation. Therefore, the inventors aim to provide a SAW resonator and its manufacturing method that can achieve a certain degree of resonant frequency modulation using the oxide of the electrode material without damaging the electrode's conductivity, and that allows the final resonant frequency of the device to be more accurately corrected to the target resonant frequency.

[0040] Based on the above analysis, this application proposes a technical approach that differs from related technologies to achieve both the accuracy of resonant frequency tuning and the reliability of the device. The core concept of this technical approach is as follows: the surface layer of the electrode is an oxide of the electrode material, and the thickness of this surface layer is within 5nm to 75nm. Based on this surface layer, the resonant frequency of the surface acoustic wave resonator is adjusted by a certain amount without damaging the conductivity of the electrode, rather than directly adjusting the resonant frequency to the target resonant frequency in one step using this surface layer. This ensures that the conductivity of the electrode is not damaged during the first adjustment process. Furthermore, a first dielectric layer with a sound velocity of 84Å / ps to 90Å / ps is added on this surface layer. This first dielectric layer can serve as a protective layer for the electrode and can also further adjust the resonant frequency after the first adjustment. This works in conjunction with the aforementioned surface layer to adjust the resonant frequency to the target frequency or closer to it. Therefore, based on the first adjustment, the accuracy of the resonant frequency adjustment is improved, while the required amount of resonant frequency adjustment in the first adjustment is reduced, i.e., the thickness requirement of the surface layer of the electrode is reduced. This avoids damage to the conductivity of the electrode due to the first adjustment, thereby ensuring the reliability of the device.

[0041] In the surface acoustic wave resonator provided according to the present invention, the first dielectric layer can be constructed to generate a predictable frequency offset (resonance frequency shift) to actively compensate for the difference between the first resonant frequency and the target resonant frequency of the surface acoustic wave resonator after the first adjustment layer, so as to form a relationship of coordinated adjustment of resonant frequency with the surface portion of the electrode. That is, the surface acoustic wave resonator provided in this application decomposes the task of resonant frequency adjustment into a first adjustment achieved by the surface portion of the electrode and a second adjustment achieved by the first dielectric layer. Based on the second adjustment and the first adjustment, the resonant frequency of the surface acoustic wave resonator is compensated to the target resonant frequency or closer to the target resonant frequency. Thus, the thickness of the surface portion of the electrode can be set in the range of 5nm to 70nm, so that it does not exceed the safety threshold that would cause electrode damage, thereby achieving a certain amount of first adjustment without causing deterioration of the electrode's conductivity. Furthermore, by setting a first dielectric layer of 84Å / ps to 90Å / ps on the surface portion of the electrode, the first dielectric layer can serve as a passivation layer for the electrode, and based on its specific sound velocity setting, a certain amount of second adjustment can be achieved. This can compensate the first resonant frequency of the surface acoustic wave resonator after the first adjustment, thereby compensating the first resonant frequency to the target resonant frequency or closer to the target resonant frequency, and thus improving the accuracy of resonant frequency adjustment based on the first adjustment. Therefore, the surface acoustic wave resonator provided in this application embodiment adjusts the resonant frequency through the surface portion of the first dielectric cooperating electrode, improving the accuracy of resonant frequency correction while ensuring the reliability of the device. It should be noted that in this application embodiment, the surface acoustic wave resonator refers to a device that utilizes the piezoelectric effect to excite and detect surface acoustic waves through electrodes (interdigital transducers) disposed on a piezoelectric substrate to achieve electrical signal resonance or filtering functions. The surface acoustic wave resonator provided in this application embodiment can be a discrete resonator or a resonant unit in a surface acoustic wave filter.

[0042] Please see Figure 1The diagram shown is a structural schematic of a surface acoustic wave (SAW) resonator 100 provided according to some embodiments of this application. The SAW resonator 100 includes a piezoelectric substrate 1, an electrode 2, and a first dielectric layer 4. The electrode 2 is disposed on the piezoelectric substrate 1 and has a surface portion 3 with a thickness of 5 nm to 75 nm. This surface portion 3 is an oxide of the forming material of the electrode 2. For example, if the electrode 2 is an aluminum electrode, then the surface portion 3 is aluminum oxide. The surface portion 3 can be obtained by oxidizing the electrode 2, i.e., the surface portion 3 is a part of the electrode 2. Oxidizing the electrode 2 to a certain depth yields the surface portion 3. The density of the surface portion 3 is higher than that of the electrode 2, thereby reducing the propagation speed of the SAW relative to the electrode 2, and thus achieving a certain amount of frequency reduction tuning of the SAW resonator, i.e., the first tuning. This reduces the resonant frequency of the surface acoustic wave resonator to a certain extent. The first dielectric layer 4 is disposed on the surface portion 3 of the electrode 2, and its sound velocity is 84 Å / ps to 90 Å / ps. Based on this sound velocity, the first dielectric layer can further adjust the resonant frequency of the surface acoustic wave resonator based on the first adjustment, to bring the resonant frequency to the target resonant frequency, or a second resonant frequency that is closer to the target resonant frequency than the first adjusted resonant frequency. Alternatively, a portion of the first dielectric layer 4 can also be disposed on the surface of the piezoelectric substrate 1 exposed by the electrode 2.

[0043] The surface acoustic wave resonator provided in this application embodiment sets the thickness of the surface portion 3 of electrode 2 within a safe threshold range that does not damage electrode 2. This allows for a first adjustment of the resonant frequency without compromising the conductivity of the electrode, ensuring device reliability. A first medium with a certain sound velocity range is then used to further adjust the resonant frequency a second time. This improves the accuracy of the resonant frequency adjustment based on the first adjustment; that is, the second resonant frequency obtained after the second adjustment is closer to the target resonant frequency than the first resonant frequency obtained after the first adjustment, or the second resonant frequency directly reaches the target resonant frequency. Therefore, the surface acoustic wave resonator provided in this application embodiment can balance the accuracy of resonant frequency adjustment and device reliability.

[0044] The piezoelectric substrate 1 is a substrate or base material possessing piezoelectric properties, capable of exciting, propagating, and receiving surface acoustic waves on its surface or within its interior. The piezoelectric substrate 1 can be a single-crystal substrate or a composite piezoelectric thin film substrate, and the piezoelectric substrate may include lithium niobate (…). ) crystal substrate or lithium tantalate ( Crystal substrate. The composite piezoelectric thin film substrate includes a carrier substrate and a piezoelectric thin film disposed on the carrier substrate; wherein, the carrier substrate can be any one of silicon carbide, glass, ceramic and silicon, and the piezoelectric thin film can be, but is not limited to, an aluminum nitride (AlN) thin film.

[0045] Electrode 2 is a conductive pattern formed on the piezoelectric substrate 1, used to realize the mutual conversion between electrical signals and surface acoustic waves. The material, shape, and number of layers of electrode 2 can vary according to the specific device design. For example, electrode 2 may include, but is not limited to: a single-layer metal electrode (such as an electrode made of at least one of aluminum, copper, gold, molybdenum, titanium, chromium, etc.) or a multilayer composite metal electrode. In this embodiment, electrode 2 can be an interdigital electrode, i.e., an electrode in an interdigital transducer. The overall material of electrode 2 or the surface material away from the piezoelectric substrate 1 can be aluminum. After the surface layer of electrode 2 is oxidized and modified, a surface portion 3 with a thickness of 5 nm to 75 nm and composed of an oxide of the electrode material is obtained. This surface portion 3 can generate a first frequency offset to adjust the resonant frequency of the surface acoustic wave resonator from the initial resonant frequency to the first resonant frequency.

[0046] In some embodiments, the surface portion 3 can be an oxide layer formed after controlled oxidation treatment of the surface of the electrode 2. The density of the surface portion 3 is higher than that of the raw material of the electrode 2, which is equivalent to generating a mass loading effect, resulting in an increase in the inertia of surface acoustic wave propagation and a corresponding decrease in the sound velocity, thereby reducing the resonant frequency. Therefore, the surface portion 3 has a frequency reduction effect, and the first frequency deviation it generates is a frequency reduction frequency deviation, that is, the resonant frequency is lower after the electrode 2 is oxidized and modified to form the surface portion 3 compared to before, thereby reducing the deviation between the initial resonant frequency and the target resonant frequency, and realizing the task of partially adjusting the resonant frequency. The surface acoustic wave resonator 100 provided in this application embodiment can use the oxide of the electrode material obtained by oxidizing the electrode 2 itself as the surface portion 3 to perform the first adjustment of the resonant frequency, without the need to provide additional frequency tuning materials with improved surface acoustic wave propagation characteristics to form a frequency tuning layer, thus achieving a simple process and low manufacturing cost.

[0047] The first dielectric layer 4 can be disposed on at least a portion of the surface layer 3 of the electrode 2. It serves both as a passivation protection function and as a frequency tuning layer that actively generates a second frequency offset for resonant frequency compensation. The first frequency offset refers to the deviation of the resonant frequency of the surface acoustic wave resonator 100 relative to the initial resonant frequency caused by the formation of the surface layer 3 of the electrode 2. For example, in this embodiment, the first frequency offset is a down-frequency offset, the magnitude of which is determined by the thickness of the surface layer 3. The second frequency offset refers to the deviation of the resonant frequency of the surface acoustic wave resonator 100 relative to the first resonant frequency obtained after the first frequency offset, caused by the formation of the first dielectric layer 4 with a sound velocity of 84 Å / ps to 90 Å / ps. For example, based on the mass loading effect and / or stiffness effect of the first dielectric layer 4, the second frequency offset can be a down-frequency offset or a up-frequency offset. Its direction and magnitude depend on the difference between the intermediate resonant frequency and the target resonant frequency, thereby compensating for this difference; that is, the magnitude of this difference determines the magnitude of the second frequency offset. By generating a second frequency offset through the first dielectric layer 4, the first resonant frequency obtained after the first adjustment can be further adjusted to the target resonant frequency or a second resonant frequency that is closer to the target resonant frequency.

[0048] It should be noted that, in this embodiment, the initial resonant frequency refers to the resonant frequency of the surface acoustic wave resonator 100 in its initial structural state before the formation of the surface portion 3 of electrode 2. That is, the initial resonant frequency is the resonant frequency of the surface acoustic wave resonator 100 in the initial structure between the formation of electrode 2 and the formation of the surface portion 3. The initial resonant frequency can be obtained by testing the test electrodes on the initial structure using probes before the surface acoustic wave resonator 100 is packaged. The first resonant frequency refers to the resonant frequency of the surface acoustic wave resonator 100 after the surface portion 3 of electrode 2 is made of an oxide of electrode material and before the formation of the first dielectric layer 4. This first resonant frequency is the resonant frequency obtained after a first adjustment of the resonant frequency based on the surface portion 3. This first resonant frequency is greater than the target resonant frequency and lies between the initial resonant frequency and the target resonant frequency, so that it can be compensated to the target frequency through subsequent second frequency offset co-compensation. The target resonant frequency refers to the predetermined resonant frequency that the surface acoustic wave resonator 100 is to achieve, i.e., the desired resonant frequency. It should be noted that the target resonant frequency can be the nominal center frequency or a frequency within an acceptable tolerance range near that center frequency.

[0049] The surface acoustic wave resonator 100 provided in this embodiment generates a first frequency offset through a surface portion 3 of electrode 2 with a certain thickness, thereby adjusting the resonant frequency of the surface acoustic wave resonator 100 from the initial resonant frequency to the first resonant frequency, instead of adjusting it to the target resonant frequency in one step. This reduces the thickness of the surface portion of electrode 2, thereby reducing the degree of oxidation on the surface of electrode 2. That is, there is no need to subject electrode 2 to excessive and damaging oxidation in order to achieve the target resonant frequency, avoiding the significant decrease in conductivity caused by excessive electrode oxidation and the resulting increase in insertion loss and power tolerance fallback. This ensures that the accurate adjustment of the resonant frequency does not affect the reliability of the device. Furthermore, a second frequency offset is generated by a first dielectric layer 4 with a certain sound velocity disposed on the surface portion 3 to compensate for the difference between the first resonant frequency and the target resonant frequency. Based on the synergistic effect of the second frequency offset of a preset size generated by the first dielectric layer 4 (the preset size of the second frequency offset can be determined based on the aforementioned difference) and electrode oxidation, the resonant frequency can be accurately adjusted to the target resonant frequency, thus ensuring the reliability of the device while accurately adjusting the resonant frequency.

[0050] In some embodiments, the frequency modulation parameter of the first dielectric layer 4 is configured to generate a second frequency offset that compensates for the aforementioned difference. That is, the frequency modulation parameter of the first dielectric layer 4 can be determined based on the aforementioned difference, thereby generating a second frequency offset of a preset size to compensate for the aforementioned difference, in conjunction with oxidation tuning, to achieve accurate tuning of the resonant frequency. Here, the frequency modulation parameter of the first dielectric layer 4 refers to the thickness of the first dielectric layer 4, or a combination thereof, which can be used to actively control the thickness of the first dielectric layer 4. Of course, in other embodiments, the frequency modulation parameter can also be mass density or elastic modulus, etc. In this embodiment, the sound velocity of the first dielectric layer is 84 Å / ps to 90 Å / ps, thereby generating a second frequency offset to compensate for the aforementioned difference, reducing the thickness of the oxidized surface portion 3 of the electrode 2, and preventing excessive oxidation of the electrode 2 that would degrade its conductivity.

[0051] In the surface acoustic wave resonator 100 provided in this application embodiment, the frequency modulation parameters (including sound velocity and / or thickness) of the first dielectric layer 4 are actively configured to generate a second frequency deviation required to compensate for the difference (the difference between the first resonant frequency and the target resonant frequency). Specifically, the frequency modulation parameters of the first dielectric layer 4 can be determined based on a preset correspondence between frequency modulation parameters and frequency conversion amounts. When determining the required frequency conversion amount, i.e., the frequency deviation, generated by the first dielectric layer 4, the required frequency modulation parameters of the first dielectric layer can be determined based on this correspondence, thereby actively configuring the frequency modulation parameters of the first dielectric layer 4. The correspondence between the frequency modulation parameters and the frequency conversion amount can be an approximately linear correspondence. By individually or in combination adjusting the sound velocity and / or thickness of the first dielectric layer 4, the amplitude of the second frequency deviation can be precisely set to match the difference between the first resonant frequency and the target resonant frequency, achieving the desired resonant frequency compensation. For example, the first dielectric layer 4 can be a silicon nitride layer, and by configuring the frequency modulation parameters of the silicon nitride layer, the second frequency offset can be linearly adjusted in the range of approximately -2.8MHz to +1.6MHz.

[0052] By using sound velocity and / or thickness as actively adjustable frequency modulation parameters, the target frequency modulation parameters of the first dielectric layer are obtained, which are ultimately the frequency modulation parameters in the surface acoustic wave resonator 100. This allows for precise setting of the second frequency deviation amplitude generated by the first dielectric layer 4 based on the difference between the first resonant frequency and the target resonant frequency, improving the accuracy and controllability of frequency compensation and thus enhancing the accuracy of resonant frequency tuning. Furthermore, using sound velocity and / or thickness as independently adjustable structural parameters allows for control through factors such as power, gas ratio, and temperature during the deposition process, providing a flexible process window for the manufacture of the surface acoustic wave resonator 100 and improving yield and consistency.

[0053] In related technologies, the first dielectric layer 4 disposed above the electrode 2 can be a silicon nitride layer. The role of the silicon nitride layer in surface acoustic wave (SAW) resonators is typically limited to providing physical protection such as moisture resistance and insulation. Although it is known that the thin-film characteristics of the silicon nitride layer affect the resonant frequency, the common practice is to treat the frequency offset of the silicon nitride layer as a passively generated factor, rather than deliberately associating this frequency offset with a specific tuning parameter to actively configure its tuning parameters so that it generates a second frequency offset with amplitude sufficient for compensation. That is, the common practice in related technologies is generally to roughly adjust the thickness of the silicon nitride layer based on passivation requirements to achieve fine-tuning of the resonant frequency, rather than utilizing the acoustic velocity and / or thickness of the silicon nitride layer as a precise, active, and independently controllable frequency compensation variable. Therefore, it cannot provide a synergistic solution to the aforementioned problems with the resonant frequency of SAW based on oxide trimming. However, in this embodiment, the frequency modulation parameters of the silicon nitride layer are actively configured so that its sound velocity is in the range of 84 Å / ps to 90 Å / ps, thereby generating a predictable second frequency offset that can compensate for the aforementioned difference by a preset size. This, in conjunction with the first tuning, balances the accuracy of the resonant frequency correction with the reliability of the device. Simultaneously, this surface acoustic wave resonator, in which the first dielectric layer 4 and the surface layer 3 perform resonant frequency tuning, can achieve a relatively large frequency tuning amplitude (with a large deviation between the initial resonant frequency and the target resonant frequency) without excessively relying on oxide tuning. This provides tolerance for large resonant frequency deviations generated during the manufacturing process of the surface acoustic wave resonator 100. Even if the deviation between the initial resonant frequency and the target resonant frequency is large, the device may not face the risk of being scrapped. Furthermore, the coordinated frequency tuning method provides accurate correction, and the tuning process does not affect the reliability of the device, thus improving the manufacturing yield.

[0054] In related technologies, silicon nitride layers, based on passivation requirements, are generally configured with high density, and their inherent sound velocity is generally greater than 90 Å / ps. This allows for a certain degree of frequency upsetting and tuning of the resonant frequency, bringing it closer to the target resonant frequency. In other words, in related technologies, silicon nitride layers are primarily used for passivation while also providing appropriate frequency upsetting. However, in the surface acoustic wave resonator provided in this application embodiment, the silicon nitride layer can achieve a certain degree of frequency reduction within the range of 84 Å / ps to 90 Å / ps. Therefore, when using the silicon nitride layer as the first dielectric layer 4, it can further reduce the first intermediate resonant frequency based on the first frequency deviation generated by the surface portion 3, thus reducing the first intermediate resonant frequency to the target resonant frequency or a second resonant frequency closer to the target resonant frequency. This allows for accurate resonant frequency tuning in conjunction with the surface portion 3 while reducing the thickness of the surface portion of the electrode 2 (i.e., reducing the oxidation level of the electrode 2), ensuring the reliability of the device.

[0055] In some embodiments, the sound velocity parameter of the silicon nitride layer is configured in the range of 84 Å / ps to 90 Å / ps. That is, using a silicon nitride layer with a sound velocity within this range as the first dielectric layer 4 allows for accurate resonant frequency tuning in conjunction with the surface layer 3. The sound velocity of the silicon nitride layer refers to the propagation speed of surface acoustic waves within it, directly affecting the contribution of the silicon nitride layer to the overall surface acoustic wave propagation characteristics. When the first resonant frequency is higher than the target resonant frequency, the sound velocity of the silicon nitride layer is configured to a low sound velocity, such as 84 Å / ps to 87 Å / ps, that can produce a negative second frequency deviation. Furthermore, the silicon nitride layer exhibits relatively "soft" acoustic characteristics, with its mass loading effect dominating, leading to a decrease in the resonant frequency. This reduces the difference between the first and target resonant frequencies, allowing the resonant frequency to be tuned down to the target resonant frequency or a second resonant frequency closer to the target resonant frequency. Of course, when the first resonant frequency is less than the target resonant frequency, the sound velocity of the silicon nitride layer can be configured to a high sound velocity that can generate a positive second frequency deviation, such as 89 Å / ps to 90 Å / ps. Furthermore, the silicon nitride layer exhibits relatively "rigid" acoustic characteristics, and its stiffness effect may dominate, even leading to an increase in the resonant frequency, thereby reducing the aforementioned difference, improving the accuracy of the resonant frequency correction, and increasing the error tolerance of the electrode oxidation modification process. Based on the above characteristics of the silicon nitride layer, the surface acoustic wave resonator 100 provided in this application uses a silicon nitride layer as the first dielectric layer and sets its sound velocity to 84 Å / ps to 90 Å / ps. This allows the second frequency deviation generated by the first dielectric layer 4 to compensate for the difference between the first intermediate resonant frequency and the target resonant frequency. This allows the thickness of the surface portion 3 of the electrode 2 to be within the range of 5 nm to 75 nm, enabling accurate resonant frequency tuning in conjunction with the first dielectric layer without damaging the conductivity of the electrode 2. If the sound velocity of the silicon nitride layer is below 84 Å / ps, its film density is set too low, which may weaken the passivation protection function and worsen the linearity of the resonant frequency shift, reducing the controllability of the resonant frequency adjustment and thus affecting the accuracy of the resonant frequency adjustment. If the sound velocity of the silicon nitride layer is above 90 Å / ps, its internal stress is too high, which may lead to poor adhesion to the piezoelectric substrate 1 or electrode 2, or even cracking or peeling, affecting the long-term reliability of the device. At the same time, a sound velocity of more than 90 Å / ps in the silicon nitride layer will cause a large positive second frequency shift in the silicon nitride layer, thus making it impossible to work with the first adjustment to continue correcting the resonant frequency from the first resonant frequency to the target resonant frequency or a second resonant frequency that is closer to the target resonant frequency.

[0056] The surface acoustic wave resonator 100 provided in this application sets the sound velocity of the silicon nitride layer in the range of 84 Å / ps to 90 Å / ps. Based on the difference between the first resonant frequency and the target resonant frequency, it can generate a second frequency offset that can both compensate for the preset size of the difference and obtain a process window with specific parameters that is compatible with PECVD (Plasma Enhanced Chemical Vapor Deposition) equipment.

[0057] In some embodiments, in order for the first dielectric layer 4 to work in conjunction with the surface portion 3 of the electrode 2 to perform frequency reduction resonant frequency tuning, the sound velocity of the first dielectric layer 4 is between 84 Å / ps and 87 Å / ps. Within this sound velocity range, the first dielectric layer 4 generates a negative frequency conversion, meaning that after forming the first dielectric layer 4 within this sound velocity range, the second resonant frequency of the surface acoustic wave resonator 100 is lower than the first resonant frequency, thereby reducing the resonant frequency of the surface acoustic wave to the target resonant frequency or closer to the target resonant frequency. Specifically, a silicon nitride layer with a sound velocity between 84 Å / ps and 87 Å / ps can be used as the first dielectric layer 4. Based on the fact that the silicon nitride layer can generate a relatively large negative frequency conversion within this sound velocity range, it is possible to compensate for the resonant frequency more effectively without damaging the conductivity of the electrode 2, even when the initial resonant frequency is significantly higher than the target resonant frequency, thus improving the accuracy of the resonant frequency tuning.

[0058] In some embodiments, to better balance the passivation function and the resonant frequency tuning effect of the first dielectric layer, the thickness of the first dielectric layer 4 can be set to 15nm to 45nm. This avoids the problem that an excessively thick first dielectric layer 4 would result in an excessive mass load, leading to excessive frequency tuning and affecting the accuracy of the resonant frequency tuning. Simultaneously, it avoids an excessively thin first dielectric layer 4 that fails to function as a passivation layer. Setting the thickness of the first dielectric layer to 15nm to 45nm allows the first dielectric layer 4 to serve as both a passivation layer and a frequency tuning layer, eliminating the need for an additional passivation layer to protect the device. This helps reduce the structural complexity and manufacturing cost of the surface acoustic wave resonator 100.

[0059] In this embodiment, the first dielectric layer 4 can also be a silicon nitride layer. Based on the excellent chemical / physical barrier properties and unique surface defect repair mechanism of the silicon nitride layer, it can provide good protection for the electrode 2 during frequency downsampling and tuning, thus improving device reliability. In some embodiments, the thickness of the silicon nitride layer is configured to be between 15 nm and 45 nm. As the first dielectric layer 4, it can ensure the basic moisture-proof, insulating, and physical protection functions required for the silicon nitride layer as a passivation layer, while making the thickness parameter a fine-tuning knob for a predictable second frequency offset. Adjusting the silicon nitride layer within this thickness range can generate a second frequency offset with a definite amplitude, providing another controllable variable for resonant frequency compensation, enhancing the flexibility and accuracy of resonant frequency compensation.

[0060] In some embodiments, to achieve a second frequency offset in the silicon nitride layer that can better compensate for the difference between the first resonant frequency and the target resonant frequency, the sound velocity of the silicon nitride layer as the first dielectric layer 4 can be between 84 Å / ps and 86 Å / ps. For example, in different embodiments, the sound velocity of the silicon nitride layer can be 84.5 Å / ps, 85 Å / ps, or 85.5 Å / ps. When the sound velocity of the silicon nitride layer is lower than 84 Å / ps, its film density is poor, and it cannot achieve a good passivation effect on the device. When its sound velocity is higher than 86 Å / ps, it cannot generate or cannot significantly generate a negative frequency offset of a certain magnitude, thus the effect of reducing the oxidation degree of electrode 2 is not significant, and it cannot ensure both the accuracy of resonant frequency tuning and the reliability of the device.

[0061] In some embodiments, the thickness of the silicon nitride layer serving as the first dielectric layer 4 can be specifically configured to be between 20 nm and 45 nm to better balance passivation and resonant frequency compensation functions. For example, in different embodiments, the thickness of the silicon nitride layer can be 17 nm, 20 nm, 23 nm, 26 nm, 29 nm, 32 nm, 35 nm, 38 nm, 41 nm, or 43 nm. If the thickness of the silicon nitride layer serving as the first dielectric layer 4 is less than 15 nm, its mass load effect is too small, and the resulting absolute value of the second frequency offset may not be sufficient to effectively compensate for the aforementioned difference. Furthermore, defects such as pinholes may exist due to the thin film layer, weakening the passivation protection effect. If the thickness of the silicon nitride layer serving as the first dielectric layer 4 is greater than 45 nm, its mass load is too large, which may lead to excessive frequency offset exceeding the control window. At the same time, an excessively thick film may cause stress accumulation, resulting in wafer warping or film cracking, increasing process instability factors.

[0062] Furthermore, to address applications with significant positive frequency deviations (i.e., initial resonant frequencies significantly higher than the target frequency), a stable and efficient frequency reduction compensation scheme is provided. In some embodiments, a silicon nitride layer with a thickness of 20 nm to 45 nm and a sound velocity of 84 Å / ps to 86 Å / ps is used as the first dielectric layer 4. Through the synergistic effect of a relatively low sound velocity and a relatively suitable thickness, the first dielectric layer 4 produces a clear and significant frequency reduction effect, stably providing a large second frequency deviation to compensate for the aforementioned large difference without excessive oxidation of the electrode 2. Specifically, to better balance the accuracy of resonant frequency correction and ensure device reliability in scenarios with large positive frequency deviations, the thickness of the silicon nitride layer as the first dielectric layer 4 can be set to 22 nm to 43 nm, and the sound velocity can be set to 85 Å / ps to 87 Å / ps. For example, in different embodiments, the thickness of the silicon nitride layer serving as the first dielectric layer 4 can be 23nm, 25nm, 27nm, 30nm, 35nm, 40nm, or 42nm; and the sound velocity of the silicon nitride layer serving as the first dielectric layer 4 can be 84.5Å / ps, 85.2Å / ps, 85.8Å / ps, or 86.4Å / ps. If the sound velocity of the silicon nitride layer serving as the first dielectric layer 4 exceeds 88Å / ps and the thickness is also too thick, the expected frequency reduction effect may not be achieved; conversely, if the thickness of the silicon nitride layer serving as the first dielectric layer 4 is too thick and the sound velocity is too low, excessive frequency reduction offset may occur, leading to over-tuning of the resonant frequency and potentially causing the passivation function to lose reliability.

[0063] In this embodiment, the first resonant frequency is greater than the target resonant frequency, and the second frequency offset is in the same direction as the first frequency offset. This typically corresponds to a scenario where the initial resonant frequency is much higher than the target frequency, requiring frequency reduction correction. The first frequency offset is generated by the oxide-modified surface layer 3, which is usually in the frequency reduction direction; the second frequency offset is generated by the first dielectric layer 4, and in this configuration, it also needs to be set in the frequency reduction direction. By ensuring that both the second and first frequency offsets are in the frequency reduction direction and keeping the intermediate resonant frequency above the target frequency, the two frequency offset effects can be accumulated in the same direction, gradually reducing the initial resonant frequency to the target frequency or to a level closer to the target resonant frequency. This avoids the problem of uncontrolled resonant frequency correction caused by incorrect compensation direction while using the first dielectric layer 4 to compensate for the aforementioned difference.

[0064] In related technologies, silicon nitride layers, used as passivation layers, are generally considered to have a fixed high velocity of sound and are used as up-frequency layers during frequency tuning. However, in the surface acoustic wave resonator 100 provided in this application embodiment, by actively configuring the tuning parameters of the silicon nitride layer, which serves as the first dielectric layer 4, it generates a negative frequency deviation, similar to the surface layer 3, thus being used as a down-frequency layer. In this way, in conjunction with the surface layer 3, the resonant frequency with a large positive deviation is accurately tuned to the target resonant frequency. This achieves accurate tuning of the resonant frequency that would otherwise be scrapped due to limitations in related technologies, thereby improving the manufacturing yield of the surface acoustic wave resonator 100.

[0065] In some embodiments, the ratio between the thickness of the surface portion 3 of electrode 2 and the thickness of electrode 2 is 5% to 15%. If the ratio between the surface portion 3 and the thickness of electrode 2 is less than 5%, the frequency reduction effect produced by the surface portion 3 is not significant. Even with coordinated resonant frequency tuning based on the first dielectric layer 4, it may ultimately be impossible to tune the resonant frequency to the target resonant frequency or a second resonant frequency that is close to the target resonant frequency (within the allowable deviation range of resonant frequency tuning). If the ratio between the surface portion 3 and the thickness of electrode 2 is greater than 15%, the presence of the surface portion 3 will significantly degrade the conductivity of electrode 2, failing to meet the requirements of the device, thereby leading to degraded device performance and a significant decrease in reliability. Therefore, in this embodiment, the ratio between the thickness of the surface portion 3 and the thickness of electrode 2 is set within this range, which can balance the accuracy of resonant frequency tuning and the reliability of the device.

[0066] In some embodiments, electrode 2 is an aluminum electrode with a thickness of 100 nm to 500 nm, allowing its surface portion to be oxidized while maintaining the electrical performance of the device, thereby achieving a certain degree of resonant frequency tuning. The surface portion 3 can be aluminum oxide, with a thickness of 10 nm to 60 nm, such as 20 nm, 30 nm, 40 nm, or 50 nm, ensuring the electrical performance of electrode 2 while also accommodating the frequency reduction amplitude generated by the surface portion 3. Please refer to [link to relevant documentation]. Figure 2 The diagram shown is a structural schematic of a surface acoustic wave resonator 100 according to other embodiments of this application. In other embodiments, the surface acoustic wave resonator 100 further includes a second dielectric layer 5 disposed on the first dielectric layer 4, and its sound velocity is less than 40 Å / ps. By continuing to provide a low-velocity dielectric layer with a sound velocity less than 40 Å / ps, i.e., the second dielectric layer 5, on the first dielectric layer 4, the second resonant frequency can be further reduced based on the frequency reduction effect of the second dielectric layer 5, building upon the second tuning of the first dielectric layer 4. This reduces the resonant frequency to the target resonant frequency or a third resonant frequency closer to the target resonant frequency. This, in conjunction with the first dielectric layer 4, further reduces the oxidation degree of the electrode 2, ensuring the reliability of the device and improving the accuracy of the resonant frequency tuning.

[0067] In some embodiments, the second dielectric layer 5 may be, but is not limited to, a silicon dioxide layer disposed on the first dielectric layer 4, for generating a third frequency offset in the same direction as the second frequency offset. Based on its frequency reduction effect, it works in conjunction with the first dielectric layer 4, which is also used as a frequency reduction layer, to jointly compensate the resonant frequency to the target resonant frequency or a third resonant frequency that is closer to the target resonant frequency. This allows the initial resonant frequency, which is significantly different from the target resonant frequency, to be reduced and corrected to the target resonant frequency without excessive oxidation of the electrode 2. This improves the error tolerance of the manufacturing process of the surface acoustic wave resonator 100, reduces the scrap rate of the device, and thus improves the manufacturing yield of the device.

[0068] When the absolute value of the second frequency deviation generated by the first dielectric layer 4 is insufficient to fully compensate for the entire difference between the first resonant frequency and the target frequency, a silicon dioxide layer is introduced as the second dielectric layer 5 as an additional frequency compensation medium. The direction of the third frequency deviation generated by the silicon dioxide layer is set to be the same as the second frequency deviation of the first dielectric layer 4. This can effectively expand the upper limit of the total frequency reduction compensation without increasing the oxidation damage of the electrode 2, making up for the insufficient compensation capability of the single first dielectric layer 4. This ensures that even when facing a larger initial positive frequency deviation, the resonant frequency can be accurately achieved through the multilayer film synergistic frequency reduction effect.

[0069] To prevent damage to the conductivity of electrode 2 during resonant frequency tuning, in some embodiments, the surface portion 3 of electrode 2 is configured such that the rate of increase in resistance is less than or equal to 10%. That is, after oxidation of the surface portion 3 of electrode 2, the rate of increase in resistance does not exceed 10%, thus ensuring that the conductivity of electrode 2 is not significantly degraded after oxidation, and still meets the electrical performance requirements of the device. The rate of increase in resistance of electrode 2 refers to the percentage increase in its series resistance after surface oxidation modification compared to its original value. The rate of increase in resistance directly reflects the degree of damage to electrode 2 caused by oxidation modification. By strictly limiting the resistance increase rate of electrode 2 to a quantitative threshold below 10%, a clear and measurable safe operating boundary is set for oxidation modification. This ensures that the oxidation modification process that generates the first frequency offset always prioritizes not significantly sacrificing the conductivity of electrode 2. The principle of non-destructive or minimal-destructive tuning is solidified at the structural parameter level, guaranteeing that the device maintains core performance indicators such as low insertion loss and high power tolerance after resonant frequency tuning. If the resistance increase rate of electrode 2 exceeds 10% after oxidation modification, it indicates excessive oxidation of electrode 2, resulting in an excessive reduction in the conductive cross-sectional area of ​​electrode 2. This leads to a significant increase in insertion loss, a decrease in the device's Q value, and increased heat generation under power signals, potentially causing reliability issues.

[0070] Please see Figure 3 As shown, it is a schematic diagram of the manufacturing method of the surface acoustic wave resonator 100 provided in some embodiments of this application. The manufacturing method of the surface acoustic wave resonator 100 includes S02, S04 and S06, and the description of each step is as follows.

[0071] S02: Provide an initial structure, which includes a piezoelectric substrate and electrodes formed on the piezoelectric substrate.

[0072] like Figure 4 As shown, this is a schematic diagram of the initial structure 101, which is an intermediate structure of the surface acoustic wave resonator 100 before resonant frequency tuning. Electrode 2 can be formed on the piezoelectric substrate 1 using processes such as physical vapor deposition, photolithography, and etching. After electrode 2 is formed on the piezoelectric substrate 1, and before packaging, when electrode 2 has not been oxidized, the resonant frequency of the initial structure 101, i.e., the initial resonant frequency of the surface acoustic wave resonator 100, can be measured by contacting the electrode pads (PADs) on the initial structure 101 with a probe.

[0073] S04: The surface layer of the electrode is oxidized and modified, with a thickness ranging from 5 nm to 75 nm.

[0074] A schematic diagram of the structure of the surface layer 3 formed by oxidizing electrode 2 is shown below. Figure 5 As shown, this structure can define an oxidation tuning structure 102, which is another intermediate structure of the surface acoustic wave resonator 100. Oxidation modification can be oxygen plasma treatment or low-temperature thermal oxidation treatment, etc. Oxidation modification makes the surface portion 3 of electrode 2 a thin and controlled oxide layer containing electrode metal. The oxidation modification process consumes some of the metal of electrode 2, introducing mass changes and alterations in acoustic characteristics, thereby causing a regular decrease in the resonant frequency. It should be emphasized that the degree of oxidation modification here is strictly limited. In this embodiment, the thickness of the surface portion of electrode 2 is set between 5nm and 75nm, and the damage to electrode 2 caused by this is controlled within a safe range. This makes it possible that the initial resonant frequency may not be corrected to the target resonant frequency in one go. The purpose is to complete the maximum resonant frequency tuning amount or the set resonant frequency tuning amount that electrode 2 can bear while ensuring its electrical performance, leaving the remaining resonant frequency deviation correction to subsequent steps.

[0075] After the oxidation modification is completed, the resonant frequency of the oxidation-modified structure 102 is tested to determine its resonant frequency. The resonant frequency obtained in this test is defined as the first resonant frequency, and the first frequency deviation generated by the surface portion 3 is determined based on the first resonant frequency and the initial resonant frequency. The first frequency deviation is the frequency shift of the first resonant frequency relative to the initial resonant frequency, and this frequency shift is generated based on the formation of the oxidation-modified surface portion 3.

[0076] S06: Deposit a first dielectric layer on the surface portion, wherein the sound velocity of the first dielectric layer is 84 Å / ps to 90 Å / ps.

[0077] When the deviation between the initial resonant frequency and the target resonant frequency is large, it is difficult to adjust the resonant frequency to the target resonant frequency simply by oxidation adjustment (first adjustment) without damaging the conductivity of electrode 2. That is, the first resonant frequency is still higher than the target resonant frequency, and the difference between the first resonant frequency and the target resonant frequency exceeds the allowable fluctuation range of the target resonant frequency. Therefore, based on the oxidation adjustment, it is necessary to further adjust the difference between the first intermediate resonant frequency and the target resonant frequency, i.e., the second adjustment. By setting the sound velocity of the first dielectric layer 4 to 84 Å / ps to 90 Å / ps, a second frequency deviation corresponding to the difference between the first resonant frequency and the target resonant frequency can be generated. By using the second frequency deviation to compensate for this difference, the resonant frequency can be accurately adjusted. Alternatively, even if the deviation between the initial resonant frequency and the target resonant frequency is relatively small, the resonant frequency can be accurately corrected by oxidation adjustment alone. However, during the oxidation adjustment process, the degree of oxidation modification may not be accurately controlled, resulting in a slight over- or under-oxidation adjustment. A second frequency offset of a preset size corresponding to the difference can be generated based on the first dielectric layer 4 to achieve the compensation effect for the difference, thereby achieving accurate adjustment of the resonant frequency.

[0078] In some embodiments, the first dielectric layer 4 is a silicon nitride layer, which is typically deposited using a PECVD process. By actively controlling the deposition process parameters based on the first difference between the first resonant frequency and the target resonant frequency during the deposition process, the sound velocity of the silicon nitride layer forming the first dielectric layer 4 can be made to be between 84 Å / ps and 90 Å / ps, thereby generating a fully predictable second frequency deviation. This allows the resonant frequency to be accurately tuned from the first resonant frequency to the target resonant frequency or a second resonant frequency closer to the target resonant frequency, wherein the second deviation between the second resonant frequency and the target resonant frequency is smaller than the first deviation. Thus, based on the synergistic tuning effect of the first dielectric layer 4, the accuracy of the device's resonant frequency tuning is improved.

[0079] In the manufacturing method provided in this application embodiment, step S06 of depositing the first dielectric layer 4 is not performed blindly, but rather employs a parameterized control method. Specifically, firstly, based on the first difference between the first resonant frequency and the target resonant frequency, and a pre-established quantitative correspondence between the tuning parameters (sound velocity and / or thickness) of the first dielectric layer 4 and the corresponding frequency shift (frequency deviation), the tuning parameters of the first dielectric layer 4, i.e., the target tuning parameters of the first dielectric layer 4, are determined when a second frequency deviation is needed to compensate for the aforementioned first difference. The aforementioned correspondence can be, but is not limited to, a relationship line or lookup table drawn through prior experiments. The first dielectric layer 4 can be, but is not limited to, a silicon nitride layer. In some embodiments, a silicon nitride layer can be deposited as the first dielectric layer, and the aforementioned correspondence between the first dielectric layer and the frequency shift specifically refers to the correspondence between the silicon nitride layer and the frequency shift. Figure 6 and Figure 7 As shown, where, Figure 6 This is a schematic diagram showing the relationship between the sound velocity and frequency conversion of a silicon nitride layer. Figure 7 This diagram illustrates the relationship between the thickness of the silicon nitride layer and the frequency conversion. Within the sound velocity range of 84 Å / ps to 90 Å / ps, the sound velocity of the silicon nitride layer and the frequency conversion are almost linearly related; similarly, within the thickness range of 15 nm to 45 nm, the thickness of the silicon nitride layer and the frequency conversion are also almost linearly related. Furthermore, from... Figure 6 and Figure 7 It is also clear that the silicon nitride layer, as both a down-conversion and up-conversion layer, must meet certain conditions in terms of its frequency modulation parameters. Here, the frequency conversion refers to the frequency deviation generated by the silicon nitride layer corresponding to the frequency modulation parameters.

[0080] Specifically Figure 6 In the diagram, the X-axis (horizontal axis) represents the sound speed of the silicon nitride layer, with the corresponding unit being angstroms per picosecond (Å / ps). The values ​​from 83 to 91 represent the mechanical wave propagation speed of the silicon nitride layer, i.e., the sound speed value. The Y-axis (vertical axis) represents the frequency conversion, with the corresponding unit being megahertz (MHz). It represents the change in resonant frequency after the silicon nitride layer is deposited as the first dielectric layer 4, relative to the time when the silicon nitride layer is not deposited. Figure 6The data points exhibit a very clear linear growth trend. As the sound velocity of the silicon nitride layer increases, its effect on the resonant frequency gradually changes from "significant frequency reduction" to "slight frequency reduction," and finally to "frequency increase." In the lower sound velocity region (the left region, such as the area from approximately 84.3 Å / ps to 88 Å / ps, especially the 84 Å / ps to 86 Å / ps region, which is comparable to the left side of the approximately 84.3 Å / ps sound velocity), the silicon nitride layer is relatively "soft" or thick, and the mass load introduced during deposition dominates, resulting in a significant frequency drop (approximately -2.8 MHz). As the sound velocity increases (shifting to the right), the stiffness of the silicon nitride layer increases or the acoustic impedance matching changes, the mass load effect weakens, and the stiffness effect strengthens. In the higher sound velocity region (the left region, such as the area from approximately 88 Å / ps to 90 Å / ps, especially the right side of the approximately 90.0 Å / ps sound velocity), the silicon nitride layer exhibits rigid characteristics, causing the frequency to actually increase (approximately +1.6 MHz). Figure 6 This explains that the sound velocity of the silicon nitride layer is a highly controllable resonant frequency adjustment knob, i.e., a frequency tuning parameter. Because the correspondence between it and the frequency conversion amount is approximately linear, a specific sound velocity can be set by precisely controlling the silicon nitride layer deposition process (such as the power, gas pressure, and temperature of PECVD) (generating a target sound velocity corresponding to the second frequency deviation that can compensate for the aforementioned difference), thereby accurately predicting and compensating for the resonant frequency deviation. Combined with the oxide trimming amount in SO2 (the resonant frequency trimming amount generated by the first trimming, i.e., the first frequency deviation), it can be determined according to... Figure 6 The corresponding relationship shown is used to determine the target sound velocity of the silicon nitride layer in order to compensate as much as possible for the remaining frequency tuning gap after oxidation tuning.

[0081] Figure 7 This also demonstrates that the thickness of the silicon nitride layer is a controllable and linear frequency adjustment variable, i.e., a frequency modulation parameter. In the embodiments of this application, the thickness of the silicon nitride layer not only serves a traditional protective function but is also endowed with the function of fine-tuning the resonant frequency. Combined with the adjustment of the sound velocity of the silicon nitride layer, it forms a flexible, precise, and non-destructive frequency collaborative compensation mechanism, effectively solving the problem of electrode performance degradation caused by oxidation trimming.

[0082] In some embodiments, the manufacturing method provided in this application can be adapted to the above-mentioned deviations, combined with... Figure 6 and Figure 7The corresponding relationship shown uses a silicon nitride layer as the first dielectric layer 4. During the deposition of the silicon nitride layer, its sound velocity and thickness are simultaneously adjusted, thereby achieving a two-dimensional resonant frequency compensation space. That is, the properties of the silicon nitride layer are adjusted from the two dimensions of sound velocity and thickness, so that it can better compensate for the aforementioned first difference. For example, if only the thickness adjustment of the silicon nitride layer is relied upon to generate the second frequency offset, the frequency offset range is limited (approximately -1.5MHz to +1.0MHz); while if only the sound velocity adjustment of the silicon nitride layer is relied upon to generate the second frequency offset, the frequency offset range (approximately -2.8MHz to +1.6MHz) is significantly wider than the range corresponding to the thickness adjustment. When a larger reduction in frequency is needed to achieve resonant frequency tuning, compensation for the resonant frequency tuning can be achieved by selecting a silicon nitride layer with a low sound velocity and a moderate thickness (e.g., a sound velocity of approximately 84.3 Å / ps and a thickness of approximately 20 nm) (total compensation of approximately -4.3 MHz). When a small increase in frequency is needed, compensation for the resonant frequency tuning can be achieved by selecting a silicon nitride layer with a high sound velocity and a relatively small thickness (e.g., a sound velocity of 90.0 Å / ps and a thickness of 20 nm) (total compensation of approximately +0.1 MHz). The resonant frequency tuning method provided in this application, which adjusts the combination of sound velocity and thickness of the silicon nitride layer, results in higher compensation accuracy of the silicon nitride layer and effectively avoids excessive oxidation of the electrode.

[0083] Please see Figure 8 As shown, it is a schematic diagram of the steps of depositing the first dielectric layer in the manufacturing method provided according to the embodiments of this application. In the embodiments of this application, the deposition of the first dielectric layer 4 on the surface portion 3 of the electrode 2 includes steps S062, S064, S066 and S068.

[0084] S062: Obtain the first resonant frequency of the surface acoustic wave resonator after oxidation modification.

[0085] S064: Based on the first difference between the first resonant frequency and the target resonant frequency, and the correspondence between the sound velocity of the first dielectric layer and the frequency conversion amount, the target sound velocity of the first dielectric layer is determined in the range of 84 Å / ps to 90 Å / ps, so that the surface acoustic wave resonator has a second resonant frequency after the first dielectric layer is formed, and the second difference between the second resonant frequency and the target resonant frequency is less than the first difference.

[0086] S066: Determine the deposition process parameters for the first medium layer based on the target sound velocity.

[0087] S068: Deposit the first medium layer on the surface portion according to the deposition process parameters.

[0088] By setting the first dielectric layer 4, the resonant frequency tuning accuracy of the surface acoustic wave resonator 100 is improved.

[0089] The first difference in S064 is the difference between the first resonant frequency and the target resonant frequency. The magnitude of this first difference determines the amount of resonant frequency adjustment required to compensate for the first dielectric layer 4, thereby determining the magnitude and direction of the second frequency offset that the first dielectric layer 4 needs to generate. During the deposition of the first dielectric layer 4, the second frequency offset is a preset desired frequency offset that the first dielectric layer 4 can generate through control of the deposition process. After determining the required frequency offset of the first dielectric layer 4, the target frequency modulation parameters of the first dielectric layer 4, i.e., the final required frequency modulation parameters, can be determined based on the correspondence between its frequency modulation parameters and frequency conversion amounts.

[0090] In some embodiments, depositing the first dielectric layer 4 may further include: determining a target thickness of the first dielectric layer 4 within a thickness range of 15 nm to 45 nm based on the first difference and the correspondence between the thickness of the first dielectric layer 4 and the frequency conversion amount, thereby enabling the first dielectric layer 4 to better balance passivation and frequency reduction adjustment functions. Based on this, the aforementioned determination of the deposition process parameters for depositing the first dielectric layer 4 based on the target sound velocity may include: determining the deposition process parameters based on the target sound velocity and target thickness of the first dielectric layer 4, thereby forming a first dielectric layer 4 with a target thickness and target sound velocity, so that the second frequency deviation can compensate for the first difference. The surface acoustic wave resonator manufacturing method provided in this application actively adjusts the sound velocity and thickness of the first dielectric layer based on the first deviation, thereby enabling the first dielectric layer 4 to generate a predictable second frequency deviation to actively compensate for the resonant frequency. This, in conjunction with the surface portion 3 of the electrode 2, ensures the reliability of the device while achieving accurate resonant frequency adjustment.

[0091] The manufacturing method provided in this application converts the actual detected frequency deviation into precise process settings for the deposition equipment, making the formation of the first dielectric layer 4 a feedback-controlled closed-loop compensation step. On the one hand, this makes the first dielectric layer 4 no longer just a passive passivation layer with fixed functions, but an active compensation layer whose acoustic properties (sound velocity) and / or geometric parameters (thickness) can be actively designed according to actual compensation needs. On the other hand, it greatly improves the accuracy and success rate of resonant frequency correction, avoiding frequency overtuning or insufficient compensation caused by blind deposition or reliance on empirical parameters. Thus, under the premise of ensuring the safety of the electrode 2, it achieves accurate correction of large resonant frequency deviations.

[0092] In some embodiments, the first dielectric layer 4 is a silicon nitride layer, and its deposition process parameters specifically include silane ( ) and ammonia ( At least one of the following: flow rate ratio, RF power, and deposition temperature. Silane and ammonia are reaction precursors for forming the silicon nitride layer. Their flow rate ratio directly determines the stoichiometric ratio of silicon and nitrogen and the hydrogen content in the silicon nitride layer, thus affecting the density and sound velocity of the silicon nitride layer. RF power affects the number and energy of active groups in the plasma, thereby affecting the deposition rate and the stress and density of the silicon nitride layer. Deposition temperature affects surface reaction kinetics and the bonding structure of the silicon nitride layer. By selecting these physical parameters that directly affect the density, stoichiometric ratio, and internal stress of the silicon nitride layer in the PECVD process, the sound velocity value of the silicon nitride layer can be precisely set by adjusting these parameters based on the established correlation between sound velocity and frequency conversion, thereby reliably achieving the desired frequency compensation effect.

[0093] Furthermore, to address the potential insufficiency of the compensation capability of a single first dielectric layer 4, this application embodiment also provides a further resonant frequency compensation and adjustment method. Specifically, after the resonant frequency is reduced to a first resonant frequency by the oxidation modification of electrode 2, this first resonant frequency is greater than the target resonant frequency, and the second frequency deviation is offset in the same direction as the first frequency deviation. At this time, if the absolute value of the generated second frequency deviation is less than the absolute value of the difference between the aforementioned first resonant frequency and the target frequency, that is, if the second difference between the second resonant frequency and the target resonant frequency is still greater than zero, it means that the first dielectric layer 4 alone cannot completely adjust the resonant frequency to the target resonant frequency or a third resonant frequency closer to the target resonant frequency. In this case, the manufacturing method provided in this application embodiment further deposits a second dielectric layer 5 with a sound velocity of less than 40 Å / ps on the surface of the first dielectric layer 4. Based on the frequency reduction effect of the second dielectric layer 5, it works in conjunction with the first dielectric layer 4, which is also used as a frequency reduction layer, to jointly compensate the resonant frequency to the target resonant frequency or a third resonant frequency that is closer to the target resonant frequency. Thus, without excessive oxidation of the electrode 2, the initial resonant frequency that is significantly different from the target resonant frequency can be reduced and corrected to the target resonant frequency. This improves the error tolerance of the surface acoustic wave resonator 100 manufacturing process, reduces the scrap rate of the device, and thus improves the manufacturing yield of the device.

[0094] In some embodiments, the second dielectric layer 5 may be, but is not limited to, a silicon dioxide layer. The silicon dioxide layer and the silicon nitride layer, which serves as the first dielectric layer 4, together generate a frequency reduction effect in the same direction to compensate for the compensation gap of the single silicon nitride layer. This ensures that the device does not need to be scrapped even when facing large frequency deviations, thus maintaining the near-zero damage characteristics of the electrode 2 during the resonant frequency correction process and expanding the range of correctable resonant frequency deviations.

[0095] In some embodiments, to achieve differentiated and precise processing of devices with different frequency deviations and avoid unnecessary damage to the electrode 2, before performing the oxidation modification step on the surface portion 3 of the electrode 2, it is necessary to classify the frequency deviation of the initial structure 101 and determine the processing strategy. The frequency deviation of the initial structure 101 refers to the deviation between the initial resonant frequency and the target resonant frequency. Based on this deviation and the maximum value of the oxidation adjustment amount, i.e., the maximum value of the absolute value of the first frequency deviation, the processing strategy for processing the initial structure 101 is determined. Here, the oxidation adjustment amount is the frequency deviation between the first resonant frequency of the surface acoustic wave resonator 100 and the initial resonant frequency after oxidation modification; and this maximum value is determined based on the constraint that the resistance increase rate of the electrode 2 due to oxidation modification is less than or equal to 10%, representing the maximum safe frequency reduction capability without damaging the conductivity of the electrode 2. When it is determined that the deviation is greater than zero (i.e., the initial frequency is higher than the target frequency), and the absolute value of the deviation is greater than the aforementioned maximum value, it means that oxidation modification of the corresponding electrode 2 within the safe range alone cannot achieve the purpose of adjusting the initial resonant frequency to the target resonant frequency. At this point, the processing strategy is determined to be a high-frequency bias correction strategy.

[0096] Subsequently, in S04, the oxidation modification is only performed when the processing strategy is determined to be a high-frequency bias correction strategy, to generate a first frequency bias, reduce the initial resonant frequency to the first resonant frequency, and then proceed to S06. By introducing a judgment logic based on the frequency bias value and electrode damage threshold before the oxidation modification step, the manufacturing method provided in this application embodiment can identify in advance those high-frequency bias devices with excessive frequency bias that cannot be met by oxidation adjustment within the safe range, and initiate a special "high-frequency bias correction strategy" for them. On the one hand, this avoids unnecessary oxidation treatment on normal or low-frequency bias devices in pursuit of compliance, and on the other hand, it ensures that the degree of oxidation modification for high-frequency bias devices is firmly limited within the safe boundary defined by a 10% resistance increase rate, thereby achieving universal protection and precise classification compensation of electrodes from the process control level.

[0097] The high-frequency deviation processing strategy refers to the process of correcting the resonant frequency of the initial structure 101 using the steps S02 to S06 described above, in order to adjust the initial resonant frequency to the target resonant frequency. When the aforementioned deviation exceeds the maximum correction amount for oxidation adjustment, the processing strategy provided in this application embodiment does not involve scrapping the initial structure 101 as in related technologies. Instead, it adjusts the initial structure 101 based on the resonant frequency correction method provided in this application embodiment, while simultaneously ensuring both the accuracy of the resonant frequency adjustment and the reliability of the device.

[0098] Please see Figure 9As shown, it is a schematic diagram of a closed-loop process flow of the manufacturing method provided according to the embodiments of this application. In some embodiments, a silicon nitride layer is used as the first dielectric layer and a silicon dioxide layer is used as the second dielectric layer. The closed-loop process flow is described as follows.

[0099] First, an initial structure 101 is provided, and then the initial resonant frequency is tested. That is, after the electrode 2 is formed, the initial structure 101 is tested based on the probe to obtain its resonant frequency as the initial resonant frequency of the surface acoustic wave resonator 100.

[0100] Next, frequency deviation is classified, that is, based on the deviation between the initial resonant frequency and the target resonant frequency, it is determined whether the frequency deviation of the surface acoustic wave resonator 100 is high-frequency deviation, normal frequency deviation, or low-frequency deviation. Among them, high-frequency deviation refers to the initial resonant frequency being higher than the target resonant frequency, and the frequency deviation between the two cannot be corrected by the oxidation adjustment of electrode 2 without damaging the conductivity. Normal frequency deviation refers to the initial resonant frequency fluctuating within the allowable fluctuation range of the target resonant frequency, and the frequency deviation between the two can be corrected by the oxidation adjustment of electrode 2 without damaging the conductivity. Low-frequency deviation refers to the initial resonant frequency being lower than the target resonant frequency.

[0101] After determining the frequency deviation classification, different processing strategies are determined for the initial structure 101 according to the different frequency deviation classifications; among them, high frequency deviation corresponds to high frequency deviation processing strategy, normal frequency deviation corresponds to normal frequency deviation processing strategy, and low frequency deviation corresponds to low frequency deviation processing strategy.

[0102] After determining the processing strategy, the initial structure 101 is subjected to resonant frequency correction processing according to the corresponding strategy. If the processing strategy is a high-frequency processing strategy, the resonant frequency offset correction processing of the initial structure 101 includes: correcting the initial resonant frequency to the first resonant frequency through limited oxidation adjustment. Here, limited oxidation adjustment refers to oxidation adjustment without damaging the electrodes, thereby protecting the electrodes 2 from damage and reserving space for subsequent frequency modulation compensation through the silicon nitride layer. If the processing strategy is a normal frequency offset processing strategy, the initial structure 101 is processed through standard small-amplitude oxidation adjustment (baseline processing under normal conditions) to correct the resonant frequency. If the processing strategy is a low-frequency offset processing strategy, the initial structure 101 is processed through skipping or very slight oxidation adjustment.

[0103] Regardless of the processing strategy, after performing oxidation adjustment, it is necessary to obtain the resonant frequency after oxidation adjustment, i.e., to remeasure the resonant frequency again. The resonant frequency after oxidation adjustment is the intermediate resonant frequency.

[0104] After obtaining the first resonant frequency, parametric collaborative compensation of the silicon nitride layer (first dielectric layer 4) is required. This involves determining the target frequency modulation parameters of the silicon nitride layer based on the difference between the first resonant frequency and the target resonant frequency, and the correspondence between the frequency modulation parameters and the frequency conversion amount of the silicon nitride layer. The silicon nitride layer deposited based on these target frequency modulation parameters can generate a frequency deviation of a certain amplitude and direction to compensate for this difference, thereby achieving compensation and correction of the resonant frequency through collaborative oxidation tuning. Different frequency deviation classifications require different deposition processes for parametric collaborative compensation of the silicon nitride layer. If the aforementioned frequency deviation is classified as high-frequency deviation, the deposition process corresponding to parametric collaborative compensation of the silicon nitride layer is: depositing a low-velocity silicon nitride layer or a silicon nitride / silicon dioxide composite layer, which can generate a mass loading effect, producing a significant frequency reduction to compensate the first resonant frequency to the target resonant frequency. If the aforementioned frequency deviation is classified as normal frequency deviation, the deposition process corresponding to parametric collaborative compensation of the silicon nitride layer is: depositing a silicon nitride layer with a reference sound velocity and thickness to maintain the basic stability of the resonant frequency. The reference sound velocity here refers to the inherent sound velocity and thickness of the silicon nitride layer, which is primarily used as a passivation layer, when there is no need to rely on silicon nitride layer compensation for oxidation adjustment. "Inherent" means that the sound velocity and thickness are configured to change accordingly without depending on the aforementioned difference. If the aforementioned frequency deviation is classified as low-frequency deviation, the deposition process corresponding to the parameterized co-compensation of the silicon nitride layer is: depositing a high-sound-velocity silicon nitride layer to enhance the stiffness effect of the silicon nitride layer, thereby achieving a certain frequency upsampling compensation effect to correct the intermediate resonant frequency to the target resonant frequency.

[0105] After the silicon nitride layer is deposited, or if a silicon dioxide layer is required, the silicon dioxide layer is deposited, and then a final resonant frequency test is performed. This test measures the corrected resonant frequency, and the result is used to determine whether the resonant frequency correction meets the target. If the corrected resonant frequency reaches the target resonant frequency, the correction is considered successful; otherwise, it is considered unsuccessful.

[0106] If the resonant frequency is determined to meet the standard, the process loop is complete; otherwise, rework is required, and the initial resonant frequency test continues.

[0107] Based on the above description, in some embodiments, before S02, the manufacturing method further includes obtaining an initial resonant frequency and determining a processing strategy, i.e., a processing path, for processing the initial structure 101 based on the deviation between the initial resonant frequency and the target resonant frequency. When the processing strategy is determined to be a high-frequency bias processing strategy, S02 to S06 are executed. Specifically, when the processing strategy is a high-frequency bias processing strategy, the oxide adjustment in S04 is a first oxide adjustment; when the processing strategy is a normal frequency bias processing strategy, the oxide adjustment in S04 is a second oxide adjustment; and when the processing strategy is a low-frequency bias processing strategy, the oxide adjustment in S06 is a third oxide adjustment. When the oxide adjustment is the first oxide adjustment, the sound velocity of the deposited silicon nitride layer in S06 is lower than a first threshold. When the oxide adjustment is the second oxide adjustment, the sound velocity of the deposited silicon nitride layer in S06 is within a reference range. When the oxide adjustment is the third oxide adjustment, the sound velocity of the deposited silicon nitride layer in S06 is higher than a second threshold. The first threshold is less than the lower limit of the benchmark range, while the second threshold is greater than the upper limit of the benchmark range.

[0108] The manufacturing method provided in this application embodiment can achieve at least one of the following technical effects: 1. Achieving wider and more precise resonant frequency compensation capabilities. "Wider" and "more precise" here refer to the improvement over resonant frequency correction methods that primarily rely on single oxide adjustments or coarse film thickness adjustments. The manufacturing method provided in this application constructs a two-dimensional compensation space by defining the sound velocity and thickness of the first dielectric layer 4 as variables that can be actively and precisely controlled to adjust its frequency offset. This enables linear and predictable resonant frequency correction within a wide range of 4.7MHz, from -3.1MHz to +1.6MHz. This provides flexibility for addressing large-range frequency deviations generated during the resonant frequency correction manufacturing process, increasing the process window and design freedom.

[0109] 2. Electrode performance is protected, and device reliability is improved. In related technologies, when faced with a large resonant frequency deviation, deep oxidation is forced, severely damaging the conductivity of electrode 2. However, in the embodiments of this application, by utilizing the sound velocity / thickness effect of the silicon nitride layer to undertake the main or partial resonant frequency compensation task, the amount of oxidation trimming can be strictly limited within a safe threshold. This ensures that the increase rate of the series resistance (Rs) of electrode 2 does not exceed 10%, thereby eliminating reliability problems such as insertion loss degradation, power tolerance reduction, and increased nonlinear distortion caused by "excessive oxidation trimming" of the electrode.

[0110] 3. Improved production yield. For initial structures where the deviation between the initial resonant frequency and the target resonant frequency exceeds the range of single oxide adjustment capability after initial resonant frequency testing, this application embodiment does not directly scrap the structure as in related technologies. Instead, based on the oxidation adjustment of the first dielectric layer 4 and the electrode 2, a wide-range resonant frequency compensation method is provided, which can "save" these originally marginal or scrapped products, accurately pulling their resonant frequencies back to the specification range. This directly broadens the tolerance of the manufacturing process and improves the overall yield of the production line.

[0111] Furthermore, this application also provides a manufacturing system for manufacturing the surface acoustic wave resonator 100 provided in this application based on the manufacturing method provided in this application. The manufacturing system includes an oxidation trimming module, a deposition module, and a control module. The oxidation trimming module is configured to perform controlled surface oxidation on the electrode 2 to obtain an oxidation-modified surface layer 3. The deposition module is configured to deposit a first dielectric layer 4 with target frequency modulation parameters based on control parameters from the control module, such that the deposited first dielectric layer 4 can generate a second frequency offset with controllable amplitude and direction. The control module is connected to the oxidation trimming module and the deposition module respectively, and is configured to perform at least some of the following operations: calculate the oxidation trimming amount in S04 and the target sound velocity of the first dielectric layer 4 in S06 based on the deviation between the initial resonant frequency and the target resonant frequency; then control the oxidation trimming module to perform oxidation trimming that does not exceed the electrode damage threshold based on the oxidation trimming amount, and control the deposition module to deposit the first dielectric layer 4 with the set process parameters, so that the sound velocity of the first dielectric layer 4 is precisely controlled at the target sound velocity, such as the range of the target sound velocity being 84.3 Å / ps to 89.7 Å / ps.

[0112] It should be noted that the elements described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0113] It should be understood that multiple components and / or parts can be provided by a single integrated component or part. Alternatively, a single integrated component or part can be divided into multiple separate components and / or parts. The use of the public designation "a" or "an" to describe a component or part does not imply the exclusion of other components or parts.

[0114] It should be understood that although terms such as “first” or “second” may be used in this disclosure to describe various elements (such as first frequency offset and second frequency offset), these elements are not defined by these terms, which are only used to distinguish one element from another.

[0115] The basic principles of this disclosure have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this disclosure are merely examples and not limitations, and should not be considered as essential features of each embodiment of this disclosure. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the scope of this disclosure to the necessity of employing the aforementioned specific details for implementation.

[0116] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A surface acoustic wave resonator, characterized in that, include: piezoelectric substrate; An electrode is disposed on the piezoelectric substrate, the surface portion of the electrode is an oxide of the electrode material, and the thickness of the surface portion is 5 nm to 75 nm; A first dielectric layer is disposed on the surface portion, and the sound velocity is 84 Å / ps to 90 Å / ps.

2. The surface acoustic wave resonator according to claim 1, characterized in that, The sound velocity of the first dielectric layer is 84 Å / ps to 87 Å / ps; and or, the thickness of the first dielectric layer is 15 nm to 45 nm.

3. The surface acoustic wave resonator according to claim 2, characterized in that, The first dielectric layer is a silicon nitride layer with a thickness of 20 nm to 45 nm and / or a sound density of 84 Å / ps to 86 Å / ps.

4. The surface acoustic wave resonator according to claim 1, characterized in that, The ratio between the thickness of the surface layer and the thickness of the electrode ranges from 5% to 15%.

5. The surface acoustic wave resonator according to claim 1, characterized in that, The oxide is aluminum oxide, and the thickness of the surface layer is 10 nm to 60 nm.

6. The surface acoustic wave resonator according to any one of claims 1 to 5, characterized in that, The surface layer is used to generate a first frequency offset to reduce the initial resonant frequency of the surface acoustic wave resonator to a first resonant frequency, and the first dielectric layer is used to generate a second frequency offset to compensate for the difference between the first resonant frequency and the target resonant frequency.

7. The surface acoustic wave resonator according to claim 1, characterized in that, It also includes a second dielectric layer disposed on the first dielectric layer, and the sound velocity is less than 40 Å / ps.

8. The surface acoustic wave resonator according to claim 7, characterized in that, The second dielectric layer is a silicon dioxide layer.

9. The surface acoustic wave resonator according to any one of claims 1 to 5, characterized in that, The surface portion causes the rate of increase in resistance of the electrode to be less than or equal to 10%.

10. A method for manufacturing a surface acoustic wave resonator as described in any one of claims 1 to 9, characterized in that, include: An initial structure is provided, the initial structure comprising a piezoelectric substrate and electrodes formed on the piezoelectric substrate; The surface layer of the electrode is oxidized and modified, and the thickness of the surface layer ranges from 5 nm to 75 nm. A first dielectric layer is deposited on the surface portion, the first dielectric layer having a sound velocity of 84 Å / ps to 90 Å / ps.

11. The manufacturing method according to claim 10, characterized in that, The deposition of the first dielectric layer on the surface portion includes: Obtain the first resonant frequency of the surface acoustic wave resonator after the oxidation modification. Based on the first difference between the first resonant frequency and the target resonant frequency, and the correspondence between the sound velocity of the first dielectric layer and the frequency conversion amount, the target sound velocity of the first dielectric layer is determined in the range of 84 Å / ps to 90 Å / ps, such that after the formation of the first dielectric layer, the surface acoustic wave resonator has a second resonant frequency, and the second difference between the second resonant frequency and the target resonant frequency is less than the first difference. Based on the target sound velocity, determine the deposition process parameters for depositing the first medium layer; The first dielectric layer is deposited on the surface portion according to the deposition process parameters.

12. The manufacturing method according to claim 11, characterized in that, The deposition of the first dielectric layer on the surface portion further includes: Based on the first difference and the correspondence between the thickness of the first dielectric layer and the frequency conversion amount, the target thickness of the first dielectric layer is determined within the range of 15nm to 45nm. The step of determining the deposition process parameters for depositing the first dielectric layer based on the target sound velocity includes: The deposition process parameters are determined based on the target sound velocity and target thickness of the first dielectric layer.

13. The manufacturing method according to claim 11, characterized in that, The first dielectric layer is a silicon nitride layer, and the deposition process parameters include at least one of the following: the flow rate ratio of silane to ammonia, radio frequency power, and deposition temperature.

14. The manufacturing method according to claim 11, characterized in that, When the second difference is greater than zero, the manufacturing method further includes: A second dielectric layer with a sound velocity range of less than 40 Å / ps is deposited on the surface of the first dielectric layer.

15. The manufacturing method according to any one of claims 10 to 14, characterized in that, Before performing the oxidative modification on the surface portion of the electrode, the method further includes: The resonant frequency of the initial structure is obtained as the initial frequency of the surface acoustic wave resonator. The processing strategy for the initial structure is determined based on the deviation between the initial resonant frequency and the target resonant frequency, and the maximum value of the oxidation adjustment amount; wherein, when the deviation is greater than zero and the absolute value of the deviation is greater than the maximum value, the processing strategy is a high-frequency offset correction strategy; wherein, the oxidation adjustment amount is the frequency offset between the first resonant frequency of the surface acoustic wave resonator after the oxidation modification and the initial resonant frequency; the maximum value is determined based on the constraint that the oxidation modification causes the resistance increase rate of the electrode to be less than or equal to 10%. The oxidation modification of the surface portion of the electrode includes: When the processing strategy is the high-frequency bias processing strategy, the surface layer of the electrode is oxidized and modified.

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