Method for manufacturing surface acoustic wave filter, processing device, and processing method for diplexer

Abstract

This invention proposes a method for fabricating a surface acoustic wave (SAW) filter with a temperature compensation structure, comprising: providing a piezoelectric substrate and forming a first electrode film on the piezoelectric substrate; fabricating a temperature compensation structure SiO2 film and forming a patterned structure on the surface of the first electrode film; performing planarization treatment on the patterned structure, including setting first, second, and third planarization friction force values, grinding the patterned structure, and simultaneously monitoring the friction force between the grinding module and the patterned structure in real time, performing a two-step polishing process to generate a SAW filter with a temperature compensation structure. The method according to this invention enables the surface of the entire filter to become planarized during the fabrication of the temperature compensation SAW filter, thereby improving the overall performance of the device.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing, specifically to a method and apparatus for fabricating a surface acoustic wave filter with a temperature compensation structure, and a method for fabricating a duplexer. Background Technology

[0002] For the fabrication of surface acoustic wave (SAW) filters, a piezoelectric substrate is typically manufactured, an electrode film is deposited on the substrate, and then a temperature compensation structure is deposited on the electrode film. However, during the deposition process, for example, when using vapor deposition to deposit the temperature compensation structure onto the electrode film, the surface of the temperature compensation structure will inevitably be uneven due to the undulations of the electrode film. This results in an uneven surface for the entire filter device, leading to a deterioration in the device's frequency characteristics. Furthermore, in other fabrication processes, varying pressures applied at different stages can cause irregular protrusions on the filter surface, affecting the overall performance of the filter device and leading to a tendency for the device to degrade. Therefore, achieving device surface planarization is a problem that urgently needs to be solved. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a method and equipment for manufacturing a surface acoustic wave filter with a temperature compensation structure. This method solves the problem that irregular protrusions on the filter surface caused by excessive or incomplete grinding during chemical polishing can affect the overall filter performance and improves the frequency characteristics of the entire device.

[0004] The objective of this invention is mainly achieved through the following technical solutions:

[0005] This invention provides a method for fabricating a surface acoustic wave (SAW) filter with a temperature compensation structure, characterized by the following steps: Step S1, providing a piezoelectric substrate and forming a first electrode film on the piezoelectric substrate; Step S2, fabricating a temperature compensation structure using vapor deposition, wherein the temperature compensation structure is a SiO2 film, and forming a patterned structure on the surface of the temperature compensation structure away from the first electrode film; Step S3, planarizing the patterned structure using chemical mechanical polishing (CMP), including setting a planarization friction force value, polishing the patterned structure using a preset polishing module, and simultaneously monitoring a second friction force between the polishing module and the patterned structure in real time; when the second friction force equals the planarization friction force value, the polishing module stops polishing, the planarization process ends, and a SAW filter with a temperature compensation structure is generated.

[0006] In some embodiments, step S3 includes: step S3-1, setting a constant load pressure for the grinding module to grind the patterned structure, and simultaneously acquiring the initial frictional force between the grinding module and the patterned structure; step S3-2, when the grinding module contacts the patterned structure with the constant load pressure, acquiring the working parameter information of the grinding module acting on the patterned structure, wherein the working parameter information includes at least the second frictional force between the grinding module and the patterned structure; step S3-3, setting the planarization frictional force value, the planarization frictional force value being a first planarization frictional force value, the first planarization frictional force value being the product of the duty cycle of the first electrode film and the initial frictional force; step S3-4, using the grinding module to grind the patterned structure, while simultaneously monitoring the second frictional force between the grinding module and the patterned structure in real time, and when the second frictional force is detected to be equal to the first planarization frictional force value, identifying and generating a termination signal as the planarization endpoint of polishing, stopping the grinding module grinding according to the termination signal, and ending the planarization process.

[0007] In some embodiments, the grinding module includes a first grinding unit, which includes a grooved grinding cloth, the grinding cloth being one of polyvinylidene fluoride, nylon, and polyacetal.

[0008] In some embodiments, the trench includes a plurality of parallel trench units, the depth of which is 10%-50% of the thickness of the patterned structure.

[0009] In some embodiments, the grinding module further includes a second grinding unit, which is a polishing slurry comprising abrasive particles, an acid-base regulator, a stabilizer, and a solvent.

[0010] In some embodiments, the abrasive particles have a core-shell structure in which a first abrasive coats a second abrasive, and the hardness of the first abrasive is less than that of the second abrasive.

[0011] In some embodiments, after step S2, the method further includes: step S4-3-1, setting a constant load pressure for the polishing module to polish the patterned structure, and simultaneously acquiring the initial frictional force between the polishing module and the patterned structure; step S4-3-2, setting a second planarization frictional force value, the second planarization frictional force value being 1.1-2 times the product of the duty cycle of the first electrode film and the initial frictional force, using a polishing module including silica polishing slurry to polish the patterned structure, and simultaneously monitoring the frictional force between the polishing module and the patterned structure in real time, and when the frictional force is detected... When the friction force is equal to the second planarization friction force value, a termination signal is generated as the planarization endpoint of the first polishing step, and the first polishing step ends; Step S4-3-3, a third planarization friction force value is set, the third planarization friction force value is the product of the duty cycle of the first electrode film and the initial friction force, and a polishing module including cerium dioxide polishing slurry is used to polish the patterned structure. At the same time, the friction force between the polishing module and the patterned structure is monitored in real time. When the friction force is equal to the third planarization friction force value, a termination signal is generated as the planarization endpoint of the second polishing step, and the second polishing step ends.

[0012] In some embodiments, the grinding module includes a concentrically arranged edge grinding module and a center grinding module. The edge grinding module includes an edge friction detection unit, and the center grinding module includes a center friction detection unit. The patterned structure is planarized using a chemical mechanical polishing method. Then, the process includes: Step S5-1, setting the same constant load pressure for the edge grinding module and the center grinding module, and simultaneously starting to grind the surface acoustic wave filter at the same angular velocity; Step S5-2, detecting the center of the top of the surface acoustic wave filter using the center detection unit. If the frictional force at the center exceeds the threshold of the planarization frictional force, a first termination signal is generated as the planarization endpoint of the center area polishing, and the center area grinding module is stopped according to the first termination signal; Step S5-3, the edge frictional force at the top of the surface acoustic wave filter is detected by the edge area detection unit. If the edge frictional force exceeds the threshold of the planarization frictional force, a second termination signal is generated as the planarization endpoint of the edge area polishing, and the edge area grinding module is stopped according to the second termination signal; Step S5-4, after both the center area grinding module and the edge area grinding module have stopped, a flat surface acoustic wave filter is generated.

[0013] The present invention also provides a surface acoustic wave filter with a temperature compensation structure, comprising a piezoelectric substrate, an electrode film and a temperature compensation structure, characterized in that the top of the surface acoustic wave filter is polished using the processing method for temperature compensation surface acoustic wave filters described above.

[0014] The present invention also provides a method for processing a duplexer, the duplexer comprising at least two first surface acoustic wave (SAW) filters and a second SAW filter composed of temperature compensation structures of different thicknesses, characterized in that the first SAW filter and the second SAW filter are polished separately or simultaneously using the method for manufacturing SAW filters with temperature compensation structures as described above.

[0015] The method for simultaneously polishing the first and second surface acoustic wave (SAW) filters using the aforementioned fabrication method with a temperature compensation structure includes: Step S6, providing a piezoelectric substrate, forming a first electrode film with a first thickness and a second electrode film with a second thickness on the piezoelectric substrate, wherein both the first and second electrode films include interdigital transducers and reflective gratings located on both sides of the interdigital transducers, and the first thickness is less than the second thickness; Step S7, fabricating a first temperature compensation structure using vapor deposition, wherein the first temperature compensation structure is a SiO2 film, and a patterned structure is formed on the surface of the first temperature compensation structure away from the first and second electrode films; Step S8, generating a normalized first planarization friction force based on the friction force characteristics acting on the top of the first SAW filter, and using the first planarization friction force to perform chemical mechanical polishing to identify the planarization endpoint on the top of the first and second SAW filters; Step S9, performing masking treatment on the planarized surface of the first SAW filter, and fabricating a second temperature compensation structure using vapor deposition, wherein the second temperature compensation structure forms a planar structure on the surface away from the second electrode film.

[0016] The method for fabricating a surface acoustic wave (SAW) filter with a temperature compensation structure, as described above, involves polishing the first SAW filter and the second SAW filter, respectively, including: Step S10, providing a piezoelectric substrate, forming a first electrode film and a second electrode film with a first thickness on the piezoelectric substrate, both the first electrode film and the second electrode film including interdigital transducers and reflective gratings located on both sides of the interdigital transducers, the first thickness being less than the second thickness; Step S11, performing masking treatment on the surface of the second electrode film, fabricating a first temperature compensation structure using vapor deposition, the first temperature compensation structure being a SiO2 film, and forming a first patterned structure away from the surface of the first electrode film; Step S12, according to the action on the first SAW filter... The frictional characteristics at the top of the first surface acoustic wave filter generate a normalized first planarization frictional force. Using this first planarization frictional force, a chemical mechanical polishing method is used to identify the planarization endpoint at the top of the first surface acoustic wave filter. In step S13, the surface of the first surface acoustic wave filter undergoes masking treatment, and a second temperature compensation structure is fabricated using vapor deposition. The second temperature compensation structure forms a second patterned structure on a surface far from the second electrode film, and the thickness of the second temperature compensation structure is greater than the thickness of the first temperature compensation structure. In step S14, a normalized second planarization frictional force is generated based on the frictional characteristics acting on the top of the second surface acoustic wave filter. Using this second planarization frictional force, a chemical mechanical polishing method is used to identify the planarization endpoint at the top of the second surface acoustic wave filter.

[0017] This invention also provides a fabrication apparatus for a surface acoustic wave filter with a temperature compensation structure, comprising: an electrode fabrication module for providing a piezoelectric substrate and forming a first electrode film on the piezoelectric substrate; a temperature compensation structure fabrication module for fabricating a temperature compensation structure using chemical vapor deposition, wherein the temperature compensation structure is a SiO2 film, and a patterned structure is formed on the surface of the temperature compensation structure away from the first electrode film; a polishing module for providing a constant load pressure; and a planarization module for planarizing the patterned structure using chemical mechanical polishing, setting a first planarization friction force value. The planarization module further includes a monitoring module, which monitors that when the friction force between the polishing module and the patterned structure is equal to the first planarization friction force value, the planarization process ends, and a surface acoustic wave filter with a temperature compensation structure is generated.

[0018] The grinding module includes: a plurality of sensors for detecting the frictional force of the patterned structure, and the sensors acquire working parameter information of the grinding module grinding the patterned structure under the constant load pressure. The working parameter information includes at least the second frictional force between the grinding module and the patterned structure when the grinding module is in contact with the patterned structure.

[0019] The planarization module is also used to set the first planarization friction force value, which is the product of the duty cycle of the electrode film and the second friction force.

[0020] The beneficial effects achieved by this invention are as follows:

[0021] The method for manufacturing a surface acoustic wave filter with a temperature compensation structure provided by this invention can identify the grinding of the temperature compensation layer of the filter during the processing of the temperature compensation surface acoustic wave filter, especially during the stage when irregular protrusions are generated on the surface of the filter due to chemical polishing. This allows the surface of the entire filter to become flatter, thereby improving the performance of the entire device. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0023] Figure 1 This is a schematic diagram of the part to be ground in an existing surface wave filter with a temperature compensation structure.

[0024] Figure 2 This is a flowchart illustrating a method for fabricating a surface acoustic wave filter with a temperature compensation structure according to an embodiment of the present invention.

[0025] Figure 3 This is a structural block diagram of a grinding module according to an embodiment of the present invention;

[0026] Figure 4 This is a practical application scenario diagram of a chemical mechanical polishing device for fabricating surface acoustic wave filters with temperature compensation structures;

[0027] Figure 5 It was applied Figure 3 A flowchart illustrating the fabrication method of a surface acoustic wave filter with a temperature compensation structure for a grinding module;

[0028] Figure 6 This is a structural framework diagram of another grinding module according to an embodiment of the present invention;

[0029] Figure 7 It was applied Figure 6 A flowchart illustrating the fabrication method of a surface acoustic wave filter with a temperature compensation structure for a grinding module;

[0030] Figure 8 This is a flowchart of a processing method for a duplexer according to an embodiment of the present invention;

[0031] Figure 9 This is a flowchart of another method for processing a duplexer according to an embodiment of the present invention;

[0032] Figure 10 This is a structural block diagram of a fabrication apparatus for a temperature-compensated surface acoustic wave filter according to an embodiment of the present invention.

[0033] Figure reference numeral: 101 - The part of the surface wave filter with temperature compensation structure to be ground;

[0034] 102 - Surface wave filter with temperature compensation structure;

[0035] 3-Grinding module, 31-First grinding unit, 32-Second grinding unit;

[0036] 41-Clamping device; 42-Carrier film; 43-Base plate; 44-Polishing pad; 45-Vessel for pouring polishing fluid;

[0037] 5-Grinding module, 51-Edge area grinding module, 52-Center area grinding module;

[0038] 81-Electrode processing module, 82-Temperature compensation structure processing module, 83-Grinding module, 84-Planing

[0039] Module Detailed Implementation

[0040] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0041] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0042] In the fabrication of surface acoustic wave (SAW) filters, especially those with temperature compensation structures, unevenness at the top of the filter is a common problem during the deposition of electrode films and the temperature compensation structure. Although some existing technologies employ chemical mechanical polishing (CMP) to grind the filter top, such as... Figure 1As shown, 101 is a surface acoustic wave (SAW) filter with a temperature compensation structure. The dashed part 101 represents the area to be polished in this SAW filter 102. Polishing is typically controlled based on experience, which may result in over-polishing or under-polishing, thus failing to solve the flattening problem of the SAW filter with a temperature compensation structure and hindering its high performance. According to the fabrication method of the SAW filter with a temperature compensation structure provided in this application, irregular protrusions on the filter surface caused by over-polishing or incomplete polishing during the processing of temperature-compensated SAW filters, especially during chemical polishing, can be intelligently identified and polished using the pressure control of the polishing device. This allows for flattening of the entire filter surface and improves the frequency characteristics of the entire device.

[0043] Example 1

[0044] A specific embodiment of the present invention provides a method for fabricating a surface acoustic wave filter with a temperature compensation structure. For example... Figure 2 The diagram shows a flowchart of a fabrication method for a surface acoustic wave filter with a temperature compensation structure, comprising:

[0045] Step S1: Provide a piezoelectric substrate and form a first electrode film on the piezoelectric substrate. The first electrode film may include an interdigital transducer and reflective grids located on both sides of the interdigital transducer.

[0046] Specifically, the process involves: first, fabricating a piezoelectric substrate for the filter. The piezoelectric substrate can be a single-crystal lithium niobate, a single-crystal lithium tantalate, or a substrate with a piezoelectric thin film on its surface. After the piezoelectric substrate is fabricated, an electrode film covering the piezoelectric substrate can be fabricated. According to the design requirements of the filter, the electrode film is configured with interdigital transducers and a pattern and structure of reflective gratings located on both sides of the interdigital transducers, such as an alternating high and low electrode arrangement structure.

[0047] Step S2: A temperature compensation structure is fabricated using vapor deposition. The temperature compensation structure is a SiO2 film, and a patterned structure is formed on the surface of the temperature compensation structure that is far from the first electrode film.

[0048] Specifically, the vapor deposition method can be either chemical vapor deposition (CVD) or physical vapor deposition (PVD). CVD utilizes various vapor-phase compounds or elements containing thin-film elements, such as Si, SiC, SiGe, SiGeC, Ge alloys, GeAs, InAs, InP, and NDC (Nitrogen-doped silicon carbide), to uniformly deposit temperature-compensating structures on the surface of the electrode film through a chemical reaction. PVD uses a target containing SiO2 to uniformly deposit temperature-compensating structures on the electrode film surface. Due to the influence of the electrode film's electrode arrangement structure, the temperature-compensating structure after vapor deposition has a similar arrangement structure to the electrode film.

[0049] Step S3 involves planarizing the patterned structure using chemical mechanical polishing (CMP). This includes setting a planarization friction force value, using a pre-set polishing module to polish the patterned structure, and simultaneously monitoring the friction force between the polishing module and the patterned structure in real time. When the friction force equals the planarization friction force value, the polishing module stops polishing, the planarization process ends, and a surface acoustic wave filter with a temperature compensation structure is generated.

[0050] Specifically, in step S2, a surface acoustic wave filter with a temperature compensation structure has been formed. However, this temperature compensation structure produces uneven protrusions, which manifest as a patterned structure with varying heights in the device's morphology. To achieve planarization of the entire device, this patterned structure needs to be polished. When using chemical mechanical polishing (CMP), a polishing module is typically used to provide a constant load pressure. This polishing module can be implemented as a polishing device specifically designed for precision devices such as semiconductors, for example, a combination of a polishing head and a polishing pad. In this embodiment, the implementation method of the polishing module is not limited. The planarization friction force value can be set empirically.

[0051] To achieve more precise and intelligent control of the chemical mechanical polishing (CMP) process, the planarization friction value can be accurately set based on the parameter information of the formed first electrode film and the unevenness of the patterned structure. To accurately obtain the friction value that allows the entire device to be planarized, i.e., the planarization friction value, the working parameter information of the polishing module acting on the patterned structure is acquired when the polishing module contacts the patterned structure under load pressure. This working parameter information includes at least the friction force between the polishing module and the patterned structure, which, for clarity, is named the second friction force. This friction force can be acquired in real-time using a pressure detection device pre-installed in the polishing module, such as a pressure sensor. When the polishing module contacts the patterned structure under load pressure, the polishing process has just begun, and the unevenness on the patterned structure has not yet been polished. The friction force between the polishing module and the patterned structure is at its maximum, and this is the initial friction force obtained. Subsequently, under a constant load pressure, a second friction force is generated between the polishing module and the patterned structure upon contact, and this second friction force is used as a reference factor for setting the planarization friction value.

[0052] Another factor to consider when setting the flattening friction force value is the duty cycle of the first electrode film, which affects the degree of grinding patterning. A first electrode film with a larger duty cycle can withstand a lower degree of grinding, while a first electrode film with a smaller duty cycle can withstand a higher degree of grinding.

[0053] In this embodiment, the planarization friction force value is set as the product of the duty cycle of the first electrode film and the initial friction force. This planarization friction force value serves as the minimum friction force between the grinding module and the patterned structure when the subsequent grinding module grinds the patterned structure. Grinding stops when the second friction force between the grinding module and the patterned structure reaches this value.

[0054] The specific explanation is as follows: the duty cycle of the first electrode film is less than 1. The initial frictional force is the frictional force measured when the grinding module just comes into contact with the patterned structure. At this time, since the grinding has just begun, the frictional force between the grinding module and the patterned structure is the greatest, and the product of the duty cycle of the first electrode film and the initial frictional force is less than this second frictional force. As the grinding module grinds the patterned structure with a constant load pressure, the unevenness on the patterned structure is gradually smoothed out, the surface of the patterned structure gradually becomes flat, and the frictional force between the grinding module and the patterned structure gradually decreases. When the second frictional force between the grinding module and the patterned structure is monitored to decrease to the first flattening frictional force value, which is the frictional force value set above based on the product of the duty cycle of the first electrode film and the initial frictional force, it is considered that the surface of the patterned structure is flat enough, and the grinding stops at this time.

[0055] When the flatness of the patterned structure is the same, i.e., the second friction force is the same, a larger fill factor of the first electrode film, such as 0.9, results in a larger first flattening friction force value. This means that grinding stops when the friction between the grinding module and the patterned structure is still relatively high. Conversely, a smaller fill factor of the first electrode film, such as 0.6, results in a smaller first flattening friction force value. This allows for a higher degree of grinding of the patterned structure, resulting in a smoother surface. Grinding stops only when the friction between the grinding module and the patterned structure is even lower.

[0056] Using the patterned structure formed by the electrode film and temperature compensation structure as a whole as a reference for planarization facilitates the acquisition of precise planarization friction force, enabling intelligent control of the chemical polishing process. In other embodiments, the operating parameter information may also include multi-dimensional data such as the current polishing temperature and humidity of the polishing module, to assist in monitoring the current polishing environment.

[0057] Since the frictional force generated by the grinding module acting on different parts of the patterned structure is not constant, it is affected by the uneven patterned structure formed. As mentioned above, the frictional force between the grinding module and the patterned structure changes during the grinding process. Therefore, it is necessary to monitor the frictional force between the grinding module and the patterned structure in real time. When the frictional force between the grinding module and the patterned structure is equal to the first flattening frictional force value, that is, there is neither over-grinding nor under-grinding, a termination signal is generated as the flattening endpoint of polishing. Polishing is stopped according to the termination signal to generate a flat surface acoustic wave filter, that is, the flattening process ends.

[0058] The surface acoustic wave filter manufacturing method according to this embodiment can precisely control the degree of grinding, automatically identify the flattening endpoint, avoid over-grinding and under-grinding, and improve the grinding quality of patterned structures with fine dimensions.

[0059] Furthermore, the design of the grinding module plays a crucial role in further improving grinding quality. For example... Figure 3As shown, the implementation of the grinding module 3 may include a first grinding unit 31, wherein the first grinding unit 31 includes a grooved grinding cloth, which is one of polyvinylidene fluoride, nylon, or polyacetal, and can be selected according to the grinding efficiency. The grooves of the first grinding unit 31 may include multiple parallel groove units, the depth of which is 10%-50% of the thickness of the patterned structure to be ground. This improves grinding efficiency, effectively extends the service life of the first grinding unit, and saves costs. Furthermore, the first grinding unit has a double-layer structure, with an upper grinding unit in contact with the temperature compensation structure and a lower grinding unit away from the temperature compensation structure. The lower grinding unit has a lower hardness than the upper grinding unit, which increases the compressibility of the first grinding unit, ensuring uniform contact between the first grinding unit and the surface acoustic wave device. This is beneficial for the consistency of surface acoustic wave device surface grinding and improves the flatness and uniformity of the ground surface acoustic wave device surface.

[0060] Furthermore, the grinding module 3 also includes a second grinding unit 32, which is a grinding fluid comprising grinding particles, an acid-base regulator, a stabilizer, and a solvent. The grinding particles have a core-shell structure where a first abrasive grain coats a second abrasive grain, and the first abrasive grain has a lower hardness than the second abrasive grain.

[0061] For example, such as Figure 4The diagram shows a practical application scenario of a chemical mechanical polishing (CMP) apparatus. The apparatus includes a working fixture 41, a support film 42, a base plate 43, a polishing pad 44, and a vessel 45 for pouring polishing slurry. In use, a wafer (not shown) is placed on the base plate 43, with the surface to be polished contacting the support film 42 of the working fixture 41, and the lower surface contacting the polishing pad 44. The wafer is clamped using the downward pressure provided by the working fixture, and the polishing pressure is adjusted. During polishing, the polishing slurry is poured through the vessel 45, and the wafer is polished by lateral rotation below the base plate. For example, a silica polishing slurry can be used, where the abrasive particles can be porous SiO2 abrasive coated with cerium dioxide. The less hard cerium dioxide is coated on the more hard silica, thus achieving flexible polishing. Cerium dioxide forms a softening layer on the outside of the SiO2 abrasive, exhibiting strong complexation properties that improve polishing efficiency. The support of the SiO2 abrasive core solves the problem of poor dispersion and agglomeration of cerium dioxide. The porous abrasive can adsorb the polishing slurry, improving the polishing rate and surface quality of the brittle SiO2 film surface, resulting in good surface precision and minimal damage. Other types of polishing slurries can also contain abrasive particles coated with cerium dioxide, titanium dioxide, or zirconium dioxide, with a weight ratio of 0.2%-5% and a particle size of 30-80 nm. The acid-base adjuster used to regulate the silica film removal efficiency can be a solvent with a pH of 4-6, amino acids, or amino acid derivatives. The stabilizer can be a non-Newtonian fluid; its addition reduces the electrostatic repulsion between abrasive particles, effectively controlling the polishing process and ensuring stability. In other embodiments, the abrasive particles can also be SiO2-coated polymer microspheres such as PS / PMMA. The solvent can be ethanol, diethyl ether, etc. The fabrication method of the surface acoustic wave filter using the above-mentioned grinding module can improve grinding efficiency, effectively extend the service life of the grinding module, and effectively control the grinding process to ensure grinding stability and improve the surface quality of the patterned structure after grinding.

[0062] Example 2

[0063] A specific embodiment of the present invention provides a method for fabricating a surface acoustic wave filter with a temperature compensation structure. The difference from Embodiment 1 is that a two-step grinding method is used to grind and polish the patterned structure of the temperature compensation structure.

[0064] like Figure 5 As shown, the fabrication method of a surface acoustic wave filter with a temperature compensation structure may include:

[0065] Step S4-1: Provide a piezoelectric substrate and form a first electrode film on the piezoelectric substrate. The first electrode film includes an interdigital transducer and a reflective grid located on both sides of the interdigital transducer.

[0066] Step S4-2 uses vapor deposition to fabricate a temperature compensation structure, which is a SiO2 film. The temperature compensation structure forms a patterned structure on the surface away from the first electrode film.

[0067] The specific implementation of steps S4-1 and S4-2 is basically the same as steps S1 and S2 in Embodiment 1, and will not be described in detail here.

[0068] The fabrication method of the surface acoustic wave filter also includes planarizing the patterned structure using chemical mechanical polishing, wherein the planarization process includes two polishing steps, as detailed below:

[0069] Step S4-3-1: Set a constant load pressure for the grinding module to grind the patterned structure, and at the same time obtain the initial friction force between the grinding module and the patterned structure.

[0070] Step S4-3-2: Set the second planarization friction force value. The method for setting the second planarization friction force value is the same as step S3 in Embodiment 1. Similarly, when the grinding module contacts the patterned structure with the load pressure, the initial friction force between the grinding module and the patterned structure is obtained. The difference from Embodiment 1 is that the second planarization friction force value is obtained by multiplying the duty cycle of the first electrode film by 1.1-2 times the product of the initial friction force.

[0071] Furthermore, a grinding module including silica polishing slurry is used to grind the patterned structure, while the friction between the grinding module and the patterned structure is monitored in real time. When the friction between the grinding module and the patterned structure obtained by grinding the patterned structure with silica polishing slurry is equal to the second planarization friction value, it is considered that the planarization endpoint of the first grinding and polishing has been reached, and a planarization termination signal for the first step of polishing is generated to end the first step of grinding and polishing.

[0072] The first step of the grinding and polishing process uses a silica grinding slurry. The main component of this slurry is silica particles. Silica has a high hardness and can grind relatively quickly. However, in order to avoid over-grinding, a large second flattening friction force value is set for the first step of the grinding and polishing process. When the friction force between the grinding module and the patterned structure is equal to the second flattening friction force value, that is, when the surface of the patterned structure is not yet very flat, the first step of the grinding and polishing process is stopped.

[0073] Step S4-3-2: Set the third flattening friction force value. The method for setting the third flattening friction force value is the same as step S3 in Embodiment 1. Similarly, when the grinding module contacts the patterned structure with the load pressure, the initial friction force between the grinding module and the patterned structure is obtained, and then the third flattening friction force value is obtained by multiplying the duty cycle of the first electrode film by the initial friction force.

[0074] Furthermore, a grinding module including cerium dioxide polishing slurry is used to grind the patterned structure. At the same time, the friction between the grinding module and the patterned structure is monitored in real time. When the friction between the grinding module and the patterned structure obtained by grinding the patterned structure with cerium dioxide polishing slurry is equal to the third planarization friction value, it is considered that the planarization endpoint of the second grinding and polishing step has been reached, and a planarization termination signal of the second polishing step is generated to end the second grinding and polishing step.

[0075] The first grinding and polishing process uses cerium dioxide polishing slurry, the main component of which is cerium dioxide particles. Cerium dioxide has low hardness and a relatively slow grinding speed, but it can perform relatively fine grinding, which can avoid over-grinding. At the same time, it can further refine the patterned structure surface that is not very smooth after the first grinding and polishing, so as to avoid the performance of the entire device being affected by the uneven deposited structure.

[0076] Moreover, the silica polishing slurry and cerium dioxide polishing slurry in this embodiment only include silica particles and cerium dioxide particles, respectively, and corresponding acid-base adjusters, stabilizers and solvents, instead of using a core-shell structure where the first abrasive coats the second abrasive, which can reduce the cost of the polishing slurry.

[0077] According to the method disclosed in this embodiment, the two-step polishing method can better control the polishing morphology. First, a high-hardness silica polishing slurry is used for coarse polishing, and then a low-hardness cerium dioxide polishing slurry is used for fine polishing. This method takes into account both polishing efficiency and fine polishing of the surface acoustic wave device surface, resulting in a higher degree of surface flatness, which is beneficial for realizing high-performance surface acoustic wave devices.

[0078] Example 3

[0079] A specific embodiment of the present invention provides a method for manufacturing a surface acoustic wave filter with a temperature compensation structure. Unlike embodiments one and two, the grinding module has been further designed, and the process of real-time monitoring of the frictional force between the grinding module and the patterned structure has also been further designed.

[0080] like Figure 6As shown, another implementation of the polishing module 5 includes a concentrically arranged edge region polishing module 51 and a center region polishing module 52. The edge region polishing module includes an edge region friction force detection unit, and the center region polishing module includes a center region friction force detection unit. Generally, the piezoelectric substrate experiences the highest pressure in the center region and the lowest pressure in the edge region. This pressure distribution is not conducive to the uniform removal of the temperature compensation structure. Due to the pressure difference between the edge and center of the patterned structure in the surface acoustic wave device, different friction forces will be generated when polishing the edge or center. Therefore, it is necessary to configure polishing detection units adapted to different regions to monitor the polishing process. If the flattening friction force acting on the center region is used to polish the edge region, it will result in a significantly thinner surface at the bevel compared to the center. This thinner edge after polishing will affect the device near the edge and may also lead to over-polishing and edge breakage.

[0081] Therefore, two types of detection units are set up. The edge grinding module 51 and the center grinding module 52 can be implemented as sensors, such as pressure detectors, located at the edge and center of the grinding head of the grinding module. These sensors can detect the forces acting at the edge and center during the grinding process in real time. After steps S1 and S2 of Embodiment 1 or steps S4-1 and S4-2 of Embodiment 2 are performed, i.e., during the planarization process of the patterned structure using chemical mechanical polishing (i.e., step S3 of Embodiment 1 or steps S4-3-1 and S4-3-2 of Embodiment 2), the grinding module of this embodiment is used to perform the following... Figure 7 Another method for fabricating a surface acoustic wave filter with a temperature compensation structure, as shown, further includes the following steps.

[0082] Step S5-1: Set the same constant load pressure for the edge area grinding module and the center area grinding module, and start grinding the surface acoustic wave filter simultaneously with the same angular velocity.

[0083] Step S5-2: The central friction force at the top of the surface acoustic wave filter is detected by the central area detection unit. If the detected central friction force exceeds the threshold of the planarization friction force, a first termination signal is generated as the planarization endpoint of the central area polishing. The central area grinding module is stopped according to the first termination signal. Consider that the grinding head includes a central grinding head and an edge grinding head. When the central grinding force reaches the planarization friction force, the central grinding head stops, while the edge grinding head continues to work.

[0084] Step S5-3: The edge friction force at the top of the surface acoustic wave filter is detected by the edge region detection unit. If the detected edge friction force exceeds the flattening friction force threshold, a second termination signal is generated, marking the flattening endpoint of edge region polishing. The edge region grinding module stops based on the second termination signal. The flattening friction force threshold is set to ensure that the edge region is not over-ground or insufficiently ground. This is because the flattening friction force acting on the center region is generally less than that on the edge region. Using the edge region flattening friction force as the threshold benchmark is more conducive to precise grinding of the edge and center regions. When both the center friction force and the edge friction force exceed the flattening friction force threshold, it is determined that the grinding of both the edge and center is sufficient, and a termination signal is generated. That is, when the edge friction force also reaches the flattening friction force, the edge grinding head stops working, and the polishing process ends.

[0085] In step S5-4, after both the central area grinding module and the edge area grinding module stop, a flat surface acoustic wave filter is generated. By controlling the grinding head in sections, the central area is prevented from being over-polished, ensuring polishing uniformity.

[0086] This reduces excessive grinding of the edges of the surface acoustic wave device with temperature compensation structure during the grinding process, thereby reducing the difference in grinding thickness between the center and the edges of the surface acoustic wave device with temperature compensation structure after grinding. By controlling the grinding head in sections, the central area is not over-polished, ensuring polishing uniformity and effectively improving the grinding uniformity of the surface acoustic wave device with temperature compensation structure, thus improving the grinding quality of the surface acoustic wave device with temperature compensation structure.

[0087] Example 4

[0088] In one specific embodiment of the present invention, a temperature-compensated surface acoustic wave filter is provided, including a piezoelectric substrate, an electrode film and a temperature compensation structure. The top of the surface acoustic wave filter is polished using the processing method of the temperature-compensated surface acoustic wave filter as described in Embodiment 1, Embodiment 2 or Embodiment 3.

[0089] Example 5

[0090] One specific embodiment of the present invention provides a method for fabricating a duplexer. The duplexer includes at least two first and second surface acoustic wave (SAW) filters composed of temperature compensation structures of different thicknesses. The first and second SAW filters can be polished separately or simultaneously using the fabrication method for temperature compensation SAW filters as described in Embodiments 1, 2, or 3. Since separate polishing can be directly implemented using Embodiments 1, 2, or 3, the method for simultaneously polishing the first and second SAW filters using the fabrication method for temperature compensation SAW filters as described in Embodiments 1, 2, or 3 is described below. Figure 8 As shown, it includes:

[0091] Step S6: Provide a piezoelectric substrate, and form a first electrode film with a first thickness and a second electrode film with a second thickness on the piezoelectric substrate. Both the first electrode film and the second electrode film include an interdigital transducer and a reflective grating located on both sides of the interdigital transducer. The first thickness is greater than the second thickness.

[0092] Step S7: A first temperature compensation structure is fabricated using a vapor deposition method. The temperature compensation structure is a SiO2 film. The first temperature compensation structure forms a patterned structure on the surface away from the first electrode film and the second electrode film.

[0093] The implementation methods of steps S6 and S7 are basically the same as those of steps S1 and S2 or steps S4-1 and S4-2, and will not be elaborated here.

[0094] Step S8: Generate a normalized first flattening friction force based on the friction force characteristics acting on the top of the first surface acoustic wave filter and the friction force characteristics acting on the top of the second surface acoustic wave filter, and use the first flattening friction force to perform chemical mechanical polishing to identify the flattening endpoint of the top of the first surface acoustic wave filter and the second surface acoustic wave filter.

[0095] During the simultaneous grinding of the first and second surface acoustic wave (SAW) filters of different thicknesses (heights), the coefficient of friction between the surfaces of different patterned structures and the grinding module changes as the polishing reaches different thicknesses. When the rotational speed of the grinding module remains constant under the polishing pressure of the first and second SAW filters, the frictional force between the tops of the two different SAW filters and the grinding module will change significantly. Therefore, selecting the normalized first flattening frictional force can eliminate the influence of fluctuations at the tops of different filters on the grinding module during grinding.

[0096] Step S9: The surface of the planarized first surface acoustic wave filter is masked, and a second temperature compensation structure is fabricated by vapor deposition. The second temperature compensation structure forms a planar structure on the surface away from the second electrode film.

[0097] The SiO2 layers of the first and second surface acoustic wave (SAW) filters can be ground to the same thickness using the same planarizing friction force. Since the electrode film thicknesses of the two SAW filters are different, the SiO2 layer of one SAW filter will be thinner. The required thickness of the SiO2 layer for the first and second SAW filters is different. A mask can be added to the SiO2 region where a thinner SAW filter is needed, while chemical vapor deposition can be used in the region where a thicker SAW filter is needed. This way, the first and second SAW filters with SiO2 layers of two different thicknesses can be obtained.

[0098] The polishing endpoint obtained by chemical mechanical polishing using this normalized planarization friction force is the planarization endpoint, which can improve the accuracy of endpoint detection and enable the tops of two surface acoustic wave filters of different thicknesses to be polished simultaneously.

[0099] Example 6

[0100] One specific embodiment of the present invention provides a method for fabricating a duplexer, the duplexer comprising at least two first surface acoustic wave (SAW) filters and a second SAW filter composed of temperature-compensated structures of different thicknesses. The method for polishing the first SAW filter and the second SAW filter using the fabrication method for temperature-compensated SAW filters as described in Embodiments 1, 2, or 3 is described below. Figure 9 As shown, it includes:

[0101] Step S10: Provide a piezoelectric substrate and form a first electrode film with a first thickness and a second electrode film with a first thickness on the piezoelectric substrate. Both the first electrode film and the second electrode film include interdigital transducers and reflective gratings located on both sides of the interdigital transducers. The first thickness is less than the second thickness.

[0102] Step S11: Mask the surface of the second electrode film and fabricate the first temperature compensation structure using vapor deposition. The first temperature compensation structure is a SiO2 film and forms a first patterned structure on the surface of the first electrode film away from the first temperature compensation structure.

[0103] The implementation methods of steps S10 and S11 are basically the same as those of steps S1 and S2, and will not be described in detail here.

[0104] Step S12: Generate a normalized first flattening friction force based on the friction force characteristics acting on the top of the first surface acoustic wave filter, and use the first flattening friction force to perform chemical mechanical polishing to identify the flattening endpoint of the top of the first surface acoustic wave filter.

[0105] During the simultaneous grinding of the first and second surface acoustic wave (SAW) filters of different thicknesses (heights), the coefficient of friction between the surfaces of different patterned structures and the grinding module changes as the polishing reaches different thicknesses. When the rotational speed of the grinding module remains constant under the polishing pressure of the first and second SAW filters, the frictional force between the tops of the two different SAW filters and the grinding module will change significantly. Therefore, selecting the normalized first flattening frictional force can eliminate the influence of fluctuations at the tops of different filters on the grinding module during grinding.

[0106] Step S13: Mask the surface of the first surface acoustic wave filter and fabricate the second temperature compensation structure using vapor deposition. The second temperature compensation structure forms a second patterned structure on the surface away from the second electrode film. The thickness of the second temperature compensation structure is greater than the thickness of the first temperature compensation structure.

[0107] Therefore, the first surface acoustic wave filter can be flattened according to the disclosed embodiments described above.

[0108] Step S14: Generate a normalized second flattening friction force based on the friction force characteristics acting on the top of the second surface acoustic wave filter, and use the second flattening friction force to perform chemical mechanical polishing to identify the flattening endpoint of the top of the second surface acoustic wave filter.

[0109] This allows for the flattening of the first surface acoustic wave (SAW) filter before the flattening of the second SAW filter. This enables separate processing of the first and second SAW filters of the duplexer.

[0110] Example 7

[0111] A specific embodiment of the present invention provides a fabrication apparatus for a temperature-compensated surface acoustic wave filter, such as... Figure 10 As shown, the fabrication apparatus for this temperature-compensated surface acoustic wave filter includes:

[0112] Electrode processing module 81 is used to provide a piezoelectric substrate and form a first electrode film on the piezoelectric substrate. The first electrode film includes interdigital transducers and reflective gratings located on both sides of the interdigital transducers. This module can fabricate the piezoelectric substrate of the filter. The fabrication method can be implemented with reference to existing technology, which is not the focus of this application. After the piezoelectric substrate is fabricated, the electrode film covering the piezoelectric substrate can be fabricated. This electrode film can also be called an IDT electrode. The pattern and structure of the interdigital transducers and the reflective gratings located on both sides of the interdigital transducers are configured according to the design requirements of the filter, such as an alternating high and low electrode arrangement structure.

[0113] The temperature compensation structure processing module 82 is used to fabricate a temperature compensation structure using vapor deposition. The temperature compensation structure is a SiO2 film, and a patterned structure is formed on the surface of the temperature compensation structure away from the first electrode film. This module can utilize various vapor-phase compounds or elements containing thin-film elements, such as Si, SiC, SiGe, SiGeC, Ge alloys, GeAs, InAs, InP, and NDC (Nitrogen-doped SiIicon Carbide), to chemically react on the surface of the formed piezoelectric substrate to generate the temperature compensation structure. The generation of the patterned structure can be designed according to requirements, but it is not the focus of this embodiment.

[0114] A polishing module 83 is used to provide a constant load pressure. This polishing module can be implemented as a polishing device specifically for precision devices such as semiconductors, for example, as a combination structure of a polishing head and a polishing pad. In this embodiment, the implementation of the polishing module is not limited. The polishing module 83 includes: multiple sensors for detecting the frictional force on the top of the surface acoustic wave filter; the sensors acquire operating parameter information of the polishing module acting on the top of the surface acoustic wave filter; the operating parameter information includes at least a second frictional force acting on the patterned structure. The polishing module also sets a constant load pressure to polish the patterned structure, and the sensors acquire the initial frictional force between the polishing module and the patterned structure.

[0115] Planarization module 84 is used to planarize the patterned structure using chemical mechanical polishing (CMP). A first planarization friction force value is set. The planarization process ends when the constant load pressure applied to the patterned structure equals the first planarization friction force value, generating a surface acoustic wave filter with a temperature compensation structure. To accurately obtain the friction force value that allows the entire device to be planarized, i.e., the first planarization friction force value, the working parameter information of the polishing module acting on the patterned structure is acquired when the polishing module contacts the patterned structure. This working parameter information includes at least a second friction force acting on the patterned structure. This information can be acquired in real-time using a pressure detection device pre-installed in the polishing module. Then, the first planarization friction force value is set. In this embodiment, the first planarization friction force is the product of the duty cycle of the first electrode film and the second friction force. Using the entire patterned structure formed by the electrode film and the temperature compensation structure as a reference for planarization facilitates obtaining an accurate planarization friction force. In other embodiments, the working parameter information may also include multi-dimensional data such as the current polishing temperature and humidity of the polishing module to assist in monitoring the current polishing environment.

[0116] The planarization module 84 is also used to set a first planarization friction force value, which is the product of the duty cycle of the first electrode film and the initial friction force. Furthermore, since the friction force generated by the polishing module acting on different parts of the patterned structure is not constant, as it is affected by the uneven patterned structure, it is necessary to monitor the friction force of the polishing module acting on the patterned structure in real time. When the planarization friction force acting on the patterned structure equals the first planarization friction force value, that is, when the force exerted by the polishing module on the entire patterned structure of the current device is exactly the calculated first planarization friction force value—meaning there is neither over-polishing nor under-polishing—a termination signal is generated to mark the end of the planarization process. Based on the termination signal, polishing is stopped to generate a flat surface acoustic wave filter, thus ending the planarization process.

[0117] In this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" means two or more. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0118] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for fabricating a surface acoustic wave filter with a temperature compensation structure, characterized in that, include: Step S1: Provide a piezoelectric substrate and form a first electrode film on the piezoelectric substrate; Step S2: A temperature compensation structure is fabricated using a vapor deposition method. The temperature compensation structure is a SiO2 film, and a patterned structure is formed on the surface of the temperature compensation structure away from the first electrode film. Step S3 involves planarizing the patterned structure using chemical mechanical polishing (CMP). This includes setting a planarization friction force value, using a pre-set polishing module to polish the patterned structure, and simultaneously monitoring the second friction force between the polishing module and the patterned structure in real time. When the second friction force equals the planarization friction force value, the polishing module stops polishing, the planarization process ends, and a surface acoustic wave filter with a temperature compensation structure is generated. Step S3 includes: Step S4-3-1: Set a constant load pressure for the grinding module to grind the patterned structure, and at the same time obtain the initial friction force between the grinding module and the patterned structure; Step S4-3-2: Set a second planarization friction force value. The second planarization friction force value is 1.1-2 times the product of the duty cycle of the first electrode film and the initial friction force. Use a polishing module including silica polishing slurry to polish the patterned structure. At the same time, monitor the friction force between the polishing module and the patterned structure in real time. When the monitored friction force is equal to the second planarization friction force value, identify and generate a termination signal as the planarization endpoint of the first polishing step, and the first polishing step ends. Step S4-3-3: Set a third planarization friction force value. The third planarization friction force value is the product of the duty cycle of the first electrode film and the initial friction force. Use a grinding module including cerium dioxide polishing slurry to grind the patterned structure. At the same time, monitor the friction force between the grinding module and the patterned structure in real time. When the monitored friction force is equal to the third planarization friction force value, identify and generate a termination signal as the planarization endpoint of the second polishing step, and the second polishing step ends.

2. A surface acoustic wave filter with a temperature compensation structure, comprising a piezoelectric substrate, an electrode film, and a temperature compensation structure, characterized in that, The top of the surface acoustic wave filter is polished using the fabrication method for a surface acoustic wave filter with a temperature compensation structure as described in claim 1.

3. A method for manufacturing a duplexer, the duplexer comprising at least two surface acoustic wave (SAW) filters, a first SAW filter and a second SAW filter, each composed of temperature compensation structures of different thicknesses, characterized in that... The first surface acoustic wave filter and the second surface acoustic wave filter are polished separately or simultaneously using the fabrication method of the surface acoustic wave filter with temperature compensation structure as described in claim 1.

4. The processing method of the duplexer according to claim 3, characterized in that, The method for fabricating a surface acoustic wave (SAW) filter with a temperature compensation structure as described in claim 1 involves simultaneously polishing the first SAW filter and the second SAW filter, including: Step S6: Provide a piezoelectric substrate, and form a first electrode film with a first thickness and a second electrode film with a second thickness on the piezoelectric substrate. Both the first electrode film and the second electrode film include an interdigital transducer and a reflective grating located on both sides of the interdigital transducer. The first thickness is less than the second thickness. Step S7: A first temperature compensation structure is fabricated using a vapor deposition method. The first temperature compensation structure is a SiO2 film. The first temperature compensation structure forms a patterned structure on the surface of the first electrode film and the second electrode film away from the first electrode film. Step S8: Generate a normalized first flattening friction force based on the friction force characteristics acting on the top of the first surface acoustic wave filter, and use the first flattening friction force to perform chemical mechanical polishing to identify the flattening endpoint of the top of the first surface acoustic wave filter and the second surface acoustic wave filter. Step S9: The surface of the first surface acoustic wave filter is flattened by masking, and a second temperature compensation structure is fabricated by vapor deposition. The second temperature compensation structure forms a flat structure on the surface away from the second electrode film.

5. The processing method of the duplexer according to claim 3, characterized in that, The method for fabricating a surface acoustic wave (SAW) filter with a temperature compensation structure as described in claim 1 is used to polish the first SAW filter and the second SAW filter respectively, including: Step S10: Provide a piezoelectric substrate, and form a first electrode film with a first thickness and a second electrode film with a second thickness on the piezoelectric substrate. Both the first electrode film and the second electrode film include an interdigital transducer and a reflective grating located on both sides of the interdigital transducer. The first thickness is less than the second thickness. Step S11: Mask the surface of the second electrode film and fabricate a first temperature compensation structure using vapor deposition. The first temperature compensation structure is a SiO2 film. A first patterned structure is formed on the first temperature compensation structure away from the surface of the first electrode film. Step S12: Generate a normalized first flattening friction force based on the friction force characteristics acting on the top of the first surface acoustic wave filter, and use the first flattening friction force to perform chemical mechanical polishing to identify the flattening endpoint of the top of the first surface acoustic wave filter. Step S13: Mask the surface of the first surface acoustic wave filter and fabricate a second temperature compensation structure using vapor deposition. The second temperature compensation structure forms a second patterned structure on the surface away from the second electrode film. The thickness of the second temperature compensation structure is greater than the thickness of the first temperature compensation structure. Step S14: Generate a normalized second flattening friction force based on the friction force characteristics acting on the top of the second surface acoustic wave filter, and use the second flattening friction force to perform chemical mechanical polishing to identify the flattening endpoint of the top of the second surface acoustic wave filter.

6. A fabrication apparatus for a surface acoustic wave filter with a temperature compensation structure, characterized in that, include: An electrode processing module is used to provide a piezoelectric substrate and form a first electrode film on the piezoelectric substrate; A temperature compensation structure processing module is used to fabricate a temperature compensation structure using a vapor deposition method. The temperature compensation structure is a SiO2 film, and the temperature compensation structure forms a patterned structure on the surface away from the first electrode film. A grinding module is used to provide a constant load pressure to grind the patterned structure, while acquiring the initial frictional force between the grinding module and the patterned structure; A planarization module is used to planarize the patterned structure using chemical mechanical polishing. A first planarization friction force value is set. The planarization module also includes a monitoring module. When the monitoring module detects that the friction force between the polishing module and the patterned structure is equal to the first planarization friction force value, the planarization process ends. A polishing module is used to polish the patterned structure. A second planarization friction force value is set, which is 1.1-2 times the product of the duty cycle of the first electrode film and the initial friction force. The polishing module, which includes a silica polishing slurry, polishes the patterned structure. At the same time, the friction force between the polishing module and the patterned structure is monitored in real time. When the monitored friction force is equal to the second planarization friction force value, a termination signal is generated as the planarization endpoint of the first polishing step, and the first polishing step ends. A third planarization friction force value is set, which is the product of the duty cycle of the first electrode film and the initial friction force. A grinding module including cerium dioxide polishing slurry is used to grind the patterned structure. At the same time, the friction force between the grinding module and the patterned structure is monitored in real time. When the monitored friction force is equal to the third planarization friction force value, a termination signal is generated as the planarization endpoint of the second polishing step, and the second polishing step ends.

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