Preparation method of pressure sensor based on flip-chip bonding process and pressure sensor

Abstract

This application relates to the field of semiconductor device technology and provides a method for fabricating a pressure sensor based on flip-chip bonding technology, as well as the pressure sensor itself. The method includes growing an oxide layer on a substrate; depositing a sensitive thin film layer on the oxide layer; depositing a piezoresistive resistor on the sensitive thin film layer; depositing a wiring layer on the sensitive thin film layer; depositing a silicon capping layer on the wiring layer; depositing stop structures of different heights and positions on the cavity of the silicon capping layer; the silicon capping layer, the sensitive thin film layer, and the wiring layer forming a closed cavity structure; the stop structures being enclosed within the closed cavity structure; etching through-silicon vias (TSVs) on the silicon capping layer and applying a redistribution layer process to connect the TSVs and the wiring layer; depositing a solder resist layer on the silicon capping layer; and etching the back side of the substrate to form a pressure-sensitive cavity. This application provides a protection method that effectively protects the component structure while maintaining or improving the response frequency and sensitivity to meet the requirements of high dynamic performance.

Description

Technical Field

[0001] This application belongs to the field of semiconductor device technology, and in particular relates to a method for fabricating a pressure sensor based on flip-chip bonding process and the pressure sensor itself. Background Technology

[0002] In related technologies, MEMS (Micro-Electro-Mechanical Systems) pressure sensors have been widely used to protect structural components from external influences, especially for applications requiring miniaturization and high precision. A MEMS pressure sensor is a high-precision, miniaturized pressure measurement device manufactured using microelectronics technology. It utilizes micromechanical structures to sense changes in external pressure and converts them into electrical signals for output.

[0003] In the design of MEMS pressure sensors, to enable applications under high dynamic pressure, one approach is to increase the dynamic range to handle a wider range of pressure variations. However, this method may lead to a decrease in the sensor's accuracy and stability within a specific pressure range. Another approach is to encapsulate the chip in oil and wrap it with a stainless steel film. While this method may provide some mechanical protection and stability, under high dynamic pressure and large pressure variations, the deformation of the film structure is significant, making it prone to overload and damage, thus affecting the sensor's response frequency and sensitivity. Therefore, these methods cannot enable MEMS pressure sensors to be used in applications requiring high dynamic signal response, limiting their application scope.

[0004] In summary, the challenge lies in finding a protection method in the design of MEMS pressure sensors that can effectively protect the component structure while maintaining or improving the response frequency and sensitivity to meet the requirements of high dynamic performance. Summary of the Invention

[0005] To overcome the problems existing in related technologies, this application provides a method for fabricating a pressure sensor based on flip-chip bonding technology and a pressure sensor, which can find a protection method that can effectively protect the component structure and maintain or improve the response frequency and sensitivity to meet the requirements of high dynamic performance.

[0006] This application is achieved through the following technical solution:

[0007] In a first aspect, embodiments of this application provide a method for fabricating a pressure sensor based on a flip-chip bonding process, comprising:

[0008] An oxide layer is grown on the substrate;

[0009] A sensitive thin film layer is disposed on the oxide layer; the sensitive thin film layer is provided with a varistor;

[0010] A wiring layer is disposed on the sensitive thin film layer;

[0011] A silicon capping layer is disposed on the wiring layer; a stop structure with different heights and positions is disposed on the cavity of the silicon capping layer; the silicon capping layer, the sensitive thin film layer, and the wiring layer form a closed cavity structure; the stop structure is surrounded within the closed cavity structure.

[0012] Silicon vias are etched in the silicon cap layer, and a redistribution layer process is applied to connect the silicon vias and the wiring layer.

[0013] A solder resist layer is applied to the silicon cap layer;

[0014] The back side of the substrate is etched to form a pressure-sensitive cavity.

[0015] In one embodiment, the wiring layer includes an insulating layer, wiring, and a bonding dielectric layer;

[0016] A wiring layer is formed on the sensitive thin film layer, including:

[0017] An insulating layer with a second preset pattern is deposited on the upper surface of the sensitive thin film layer; a cavity is reserved in the center of the insulating layer;

[0018] Wiring and bonding dielectric layers are disposed on the insulating layer; the wiring is used to connect the sensitive thin film layer and the silicon capping layer; a cavity is reserved in the center of the silicon capping layer; the bonding dielectric layer is used to bond the insulating layer and the silicon capping layer.

[0019] In one embodiment, a silicon capping layer is disposed on the wiring layer, including:

[0020] The preset position of the stop structure is determined based on the degree of deformation in different regions of the sensitive thin film layer;

[0021] By using a self-aligned process, the silicon capping layer is etched stepwise at a preset position to form a stop structure of different heights, which matches the deformation degree of different areas of the sensitive thin film layer.

[0022] The silicon capping layer with a stop structure is bonded to the wiring layer.

[0023] In one embodiment, the height range of the stop structure satisfies that the upper surface of the stop structure is within the maximum movable position range of the sensitive thin film layer, and is within the movable position range of less than the Von mise stress of the sensitive thin film layer.

[0024] In one embodiment, the method for fabricating a pressure sensor based on flip-chip bonding, after etching through-silicon vias in the silicon capping layer and before depositing a solder resist layer on the silicon capping layer, further includes:

[0025] Electroplating is performed on the silicon vias within the silicon capping layer to form a metal layer;

[0026] A third preset pattern is filled with dielectric material on the metal layer and silicon capping layer to form an isolation layer.

[0027] In one embodiment, a sensitive thin film layer is formed on the oxide layer, comprising:

[0028] Growing sensitive films on oxide layers;

[0029] A groove of a first preset pattern is etched on the sensitive thin film;

[0030] A varistor is placed in the groove of the first preset pattern to form a sensitive thin film layer.

[0031] In one embodiment, the method for fabricating a pressure sensor based on flip-chip bonding further includes:

[0032] Design a dedicated grounding hole to connect the inversion layer of the substrate and the silicon capping layer.

[0033] In one embodiment, the oxide layer is grounded.

[0034] In one embodiment, the internal pressure of the enclosed cavity structure is less than one atmosphere.

[0035] Secondly, this application provides a pressure sensor based on flip-chip bonding technology, which is fabricated using the fabrication method of the pressure sensor based on flip-chip bonding technology as described in the first aspect, and includes, from bottom to top, a substrate, an oxide layer, a sensitive thin film layer, a wiring layer, a silicon capping layer and a solder resist layer.

[0036] The sensitive thin film layer is equipped with a piezoresistor; the cavity of the silicon capping layer is equipped with stop structures of different heights and positions; the silicon capping layer, the sensitive thin film layer, and the wiring layer form a closed cavity structure; the stop structures are surrounded within the closed cavity structure; a silicon via is provided in the silicon capping layer, and the silicon via is connected to the wiring layer; a pressure-sensitive cavity is provided on the back side of the substrate.

[0037] The beneficial effects of the embodiments in this application compared with the prior art are:

[0038] In this embodiment, by setting a stop structure on the cavity of the silicon capping layer, together with the sensitive thin film layer and the wiring layer, a closed cavity structure is formed, allowing the sensitive thin film layer to directly face the external environment without the need for an additional protective layer or dielectric layer. Directly exposing the silicon film to the external environment reduces the dielectric obstruction during signal transmission, thereby improving the response frequency of the sensor.

[0039] In applications of dynamic pressure sensors, the sensors often need to withstand significant pressure and vibration. Traditional sensor designs often struggle to withstand these extreme conditions, easily leading to structural damage or failure. However, this fabrication method incorporates a stop structure. By setting stop structures at different heights and positions, it can effectively support and protect the sensitive thin film layer under various pressure conditions. When the sensor is subjected to excessive pressure or resonance, the stop structure can absorb some energy, reducing the impact and damage to the silicon film. This significantly improves the sensor's pressure resistance and resonance resistance, thereby avoiding the risk of structural damage and failure.

[0040] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this specification. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of this application, 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 some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic flowchart of a method for fabricating a pressure sensor based on flip-chip bonding technology according to an embodiment of this application;

[0043] Figure 2 This is a schematic diagram of the structure of a pressure sensor based on flip-chip bonding technology provided in an embodiment of this application;

[0044] Figure 3 This is a schematic diagram of another pressure sensor based on flip-chip bonding technology provided in an embodiment of this application;

[0045] Figure 4 This is a cross-sectional schematic diagram of a stop structure provided in an embodiment of this application; Figure 4 (a) is a loop stop structure. Figure 4 (b) is a discontinuous loop stop structure;

[0046] Figure 5 This is a schematic diagram of the structure of another pressure sensor based on flip-chip bonding technology provided in an embodiment of this application. Detailed Implementation

[0047] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0048] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0049] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0050] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0051] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0052] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0053] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0054] Figure 1This is a schematic flowchart of a method for fabricating a pressure sensor based on flip-chip bonding technology according to an embodiment of this application. Figure 2 This is a schematic diagram of the structure of a pressure sensor based on flip-chip bonding technology according to an embodiment of this application. (Refer to...) Figure 1 and Figure 2 The fabrication method of pressure sensors based on flip-chip bonding technology is described in detail below:

[0055] A method for fabricating a pressure sensor based on flip-chip bonding technology, comprising:

[0056] Step 101: Grow an oxide layer on the substrate.

[0057] For example, a uniform, high-quality silicon dioxide layer is typically grown on the surface of a clean substrate (such as a silicon wafer) using methods such as thermal oxidation or chemical vapor deposition (CVD). This oxide layer acts as an isolation layer between the sensitive thin film layer and the substrate, preventing impurities in the substrate from diffusing into the sensitive thin film layer while providing insulation to ensure the stability and reliability of the sensor.

[0058] Step 102: Set a sensitive thin film layer on the oxide layer.

[0059] The sensitive thin film layer is equipped with a varistor.

[0060] For example, step 102 includes: growing a sensitive film on an oxide layer; etching a groove of a first preset pattern on the sensitive film; and placing a varistor in the groove of the first preset pattern to form a sensitive film layer.

[0061] For example, the sensitive thin film layer is typically deposited on an oxide layer using methods such as sputtering, evaporation, or chemical vapor deposition. This process involves depositing a thin film material with a piezoresistive effect, such as silicon, germanium, or their alloys. A piezoresistor is specifically designed and fabricated within this thin film. The sensitive thin film layer is the core component of the sensor; it converts changes in external pressure into changes in resistance, thereby enabling pressure measurement. The piezoresistor is the key element in this conversion process.

[0062] Step 103: Set a wiring layer on the sensitive thin film layer.

[0063] For example, the wiring layer, formed through metal deposition and patterning processes, is responsible for connecting the varistor in the sensitive thin-film layer to the external circuitry. The wiring layer typically uses metals with good electrical conductivity, such as copper, aluminum, or gold. The wiring layer provides the electrical connection between the internal and external circuitry of the sensor, enabling the sensor to function properly and transmit measurement signals.

[0064] Step 104: Deposit a silicon capping layer on the wiring layer.

[0065] The silicon capping layer has stop structures at different heights and positions on its cavity; the silicon capping layer, the sensitive thin film layer, and the wiring layer form a closed cavity structure; the stop structures are enclosed within the closed cavity structure.

[0066] For example, the silicon capping layer is formed on polycrystalline silicon material using methods such as chemical vapor deposition, and it has a certain thickness and strength. Stop structures of varying heights and positions are specially designed and fabricated on the cavity of the silicon capping layer. The silicon capping layer not only provides protection for the sensor but also enables precise control of the sensor's internal space through its stop structures. The enclosed cavity structure allows the sensor to respond more sensitively to changes in external pressure.

[0067] Step 105: Etch through-silicon vias in the silicon cap layer and apply a redistribution layer process to connect the through-silicon vias and the wiring layer.

[0068] For example, through-silicon vias (TSVs) are first fabricated on the silicon cap layer using an etching process, and then an electrical connection is formed between the TSVs and the wiring layer using a redistribution layer (RDL) process. The TSV and redistribution layer processes allow for more flexible connection between the internal circuitry of the sensor and external circuitry.

[0069] Step 106: Apply a solder resist layer to the silicon capping layer.

[0070] For example, the solder mask layer is typically formed by coating and curing a layer of solder mask ink, which covers the silicon capping layer and leaves necessary openings for external connections. This protects the internal circuitry of the sensor from external environmental corrosion and interference, while providing reliable external connection points.

[0071] Step 107: Etch the back side of the substrate to form a pressure-sensitive cavity.

[0072] For example, a pressure-sensitive cavity of a certain shape and size is fabricated on the back side of a substrate using an etching process. This cavity is connected to a closed cavity structure inside the sensor, allowing the sensor to sense changes in external pressure more directly.

[0073] This embodiment sets a stop structure on the cavity of the silicon capping layer, which together with the sensitive thin film layer and the wiring layer forms a closed cavity structure. This allows the sensitive thin film layer to directly face the external environment without the need for an additional protective layer or dielectric layer. Directly exposing the silicon film to the external environment reduces the dielectric obstruction during signal transmission, thereby improving the response frequency of the sensor.

[0074] In the application scenarios of dynamic pressure sensors, the sensors often need to withstand large pressure and vibration. Traditional sensor designs are often unable to withstand these extreme conditions, which can easily lead to structural damage or failure. However, this fabrication method can effectively support and protect the sensitive thin film layer under different pressure conditions by adding a stop structure and setting stop structures at different heights and positions.

[0075] In one embodiment, see Figure 3 The wiring layer includes an insulating layer, wiring, and a bonding dielectric layer. The process of setting the wiring layer on the sensitive thin film layer is described in detail. Step 103 includes:

[0076] First, an insulating layer with a second predetermined pattern is deposited on the upper surface of the sensitive thin film layer. A cavity is reserved in the center of the insulating layer.

[0077] Then, wiring and bonding dielectric layers are formed on the insulating layer. The wiring is used to connect the sensitive thin film layer and the silicon capping layer; a cavity is reserved in the center of the silicon capping layer; and the bonding dielectric layer is used to bond the insulating layer and the silicon capping layer.

[0078] In one embodiment, the process of forming a silicon capping layer on the wiring layer is specifically described. Step 104 includes:

[0079] First, the preset position of the stop structure is determined based on the degree of deformation in different regions of the sensitive thin film layer.

[0080] For example, the deformation degree varies in different regions of the sensitive thin film layer. Since the two sides of different regions of the sensitive thin film layer are fixed, the deformation degree in the middle of the layer is larger, while the deformation degree on both sides is smaller. However, the vibration frequency on both sides is higher, which can easily lead to resonance or harmonic resonance in high dynamic pressure applications, increasing deformation and causing overload and damage to the membrane structure. Therefore, based on the deformation degree of different regions of the sensitive thin film layer, in order to make the stop structure more easily absorb vibration energy and prevent excessive deformation of the membrane structure, the height of the stop structure in the middle region is smaller than the height of the stop structures on both sides. The number of stop structures at different heights and positions is not limited and can be set according to actual conditions, for example, 3-5. Here, this embodiment is a stop structure designed for membrane structure resonance in a piezoresistive pressure sensor, not for fixing and supporting the device.

[0081] Considering that the size of the enclosed cavity structure varies in different sensors, the specific height of the stop structure cannot be determined. However, the position of the upper surface of the stop structure in contact with the sensitive thin film layer can be limited to better achieve resonance protection. Therefore, the height range of the stop structure satisfies the following conditions: the upper surface of the stop structure is within the maximum movable range of the sensitive thin film layer, and within the movable range of the Von mise stress of the sensitive thin film layer. The Von mise stress criterion is: when the equivalent stress-strain state at a certain point reaches a certain constant value related to the stress-strain state, the material yields.

[0082] For example, considering that the sensor needs to adapt to different pressure ranges, the stop structure shape can be designed as a loop stop structure or a discontinuous loop stop structure. By adjusting the size and shape of the stop structure, accurate measurement of different pressure ranges can be achieved. Figure 4 As shown, Figure 4 (a) is a loop stop structure. Figure 4 (b) is a breakpoint loop stop structure, and the number of breakpoints is not limited. In addition, the ring-shaped or end-point ring-shaped stop structure can better guide the pressure distribution, so that the pressure can be applied to the sensitive film layer more evenly, reduce stress concentration, and prevent the sensitive film layer from being damaged due to excessive stress. At the same time, by optimizing the shape and size of the stop structure, unnecessary material usage is reduced, thereby reducing the overall weight of the sensor.

[0083] Then, through a self-aligned process, the silicon capping layer is etched stepwise at preset positions to form stop structures of different heights, matching the deformation degree of different areas of the sensitive thin film layer.

[0084] Finally, the silicon capping layer with the stop structure is bonded to the wiring layer.

[0085] In one embodiment, see Figure 5 The fabrication method of a pressure sensor based on flip-chip bonding technology, after etching through-silicon vias in the silicon capping layer and before applying a solder resist layer on the silicon capping layer, further includes:

[0086] The silicon vias within the silicon capping layer are electroplated to form a metal layer; a third preset pattern is then applied to the metal layer and the silicon capping layer to form an isolation layer.

[0087] For example, the electroplated metal layer can ensure the electrical connection of the through-silicon via (TSV) within the sensor's internal circuitry, while also enhancing its mechanical strength, making it more resilient to external environmental factors such as pressure and vibration, thereby improving the overall reliability of the sensor. The electroplated metal layer can also protect the TSV from damage such as oxidation and corrosion, extending the sensor's lifespan.

[0088] The dielectric-filled isolation layer isolates the through-silicon vias and metal layers from the external environment, preventing deformation and cracking caused by changes in environmental factors such as temperature and humidity. Simultaneously, the isolation layer protects the internal circuitry of the sensor from malfunctions caused by short circuits and leakage. Furthermore, the dielectric-filled isolation layer provides a flat and uniform substrate for subsequent solder mask layer application and encapsulation processes.

[0089] In one embodiment, the method for fabricating a pressure sensor based on flip-chip bonding further includes:

[0090] A dedicated grounding via is designed to connect the inversion layer (heavily N-doped) of the substrate and the silicon capping layer. The inversion layer and silicon capping layer enclose the varistor in an equipotential region, which can prevent external interference.

[0091] In one embodiment, the oxide layer can be grounded. The oxide layer above the varistor acts as a shielding layer, and the grounded shielding layer reduces interference from the external environment on the pressure signal.

[0092] In one embodiment, the internal pressure of the closed cavity structure is less than one atmosphere, ranging from 1 Pa to several hundred Pa. The natural frequency of the closed cavity structure is closely related to its internal pressure. When the internal pressure decreases, the stiffness of the cavity structure may change, thereby causing a change in its natural frequency. This helps to make the natural frequency of the cavity structure no longer match the frequency of the external excitation, thus reducing the probability of resonance.

[0093] The method for fabricating a pressure sensor based on flip-chip bonding in this application embodiment sets a stop structure on the cavity of the silicon capping layer, which together with the sensitive thin film layer and the wiring layer forms a closed cavity structure. This allows the sensitive thin film layer to directly face the external environment without the need for an additional protective layer or dielectric layer. Directly exposing the silicon film to the external environment reduces the dielectric obstruction during signal transmission, thereby improving the response frequency of the sensor.

[0094] In applications of dynamic pressure sensors, the sensors often need to withstand significant pressure and vibration. Traditional sensor designs often struggle to withstand these extreme conditions, easily leading to structural damage or failure. However, this fabrication method incorporates a stop structure. By setting stop structures at different heights and positions, it can effectively support and protect the sensitive thin film layer under various pressure conditions. When the sensor is subjected to excessive pressure or resonance, the stop structure can absorb some energy, reducing the impact and damage to the silicon film. This significantly improves the sensor's pressure resistance and resonance resistance, thereby avoiding the risk of structural damage and failure.

[0095] See Figures 2 to 5This application provides a pressure sensor based on flip-chip bonding technology, which is fabricated using the flip-chip bonding technology fabrication method described in the above embodiments. From bottom to top, it includes a substrate, an oxide layer, a sensitive thin film layer, a wiring layer, a silicon capping layer, and a solder resist layer.

[0096] The sensitive thin film layer is equipped with a piezoresistor; the cavity of the silicon capping layer is equipped with stop structures of different heights and positions; the silicon capping layer, the sensitive thin film layer, and the wiring layer form a closed cavity structure; the stop structures are surrounded within the closed cavity structure; a silicon via is provided in the silicon capping layer, and the silicon via is connected to the wiring layer; a pressure-sensitive cavity is provided on the back side of the substrate.

[0097] For example, the stop structure shape design can be a loop stop structure or a discontinuous loop stop structure.

[0098] For example, a pressure sensor based on flip-chip bonding also includes a metal layer and an insulating layer.

[0099] The silicon vias within the silicon capping layer are electroplated to form a metal layer. A third pre-defined dielectric filler is then applied to the metal layer and the silicon capping layer to form an isolation layer.

[0100] For the beneficial effects of the pressure sensor based on the flip-chip bonding process, please refer to the beneficial effects of the fabrication method of the pressure sensor based on the flip-chip bonding process in the above embodiments.

[0101] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0102] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A method for fabricating a pressure sensor based on flip-chip bonding technology, characterized in that, The pressure sensor is a dynamic pressure sensor; the method includes: An oxide layer is grown on the substrate; A sensitive thin film layer is disposed on the oxide layer; a varistor is disposed on the sensitive thin film layer; A wiring layer is disposed on the sensitive thin film layer; A silicon capping layer is disposed on the wiring layer; stop structures of different heights and positions are disposed on the cavity of the silicon capping layer; the silicon capping layer, the sensitive thin film layer, and the wiring layer form a closed cavity structure; the stop structures are surrounded within the closed cavity structure; the process of disposing the silicon capping layer on the wiring layer includes: determining the preset positions of the stop structures according to the deformation degree of different regions of the sensitive thin film layer; etching the silicon capping layer stepwise at the preset positions using a self-aligned process to form stop structures of different heights to match the deformation degree of different regions of the sensitive thin film layer, wherein the height of the stop structure disposed in the middle region of the cavity of the silicon capping layer is smaller than the height of the stop structures disposed on both sides; and bonding the silicon capping layer with the stop structures to the wiring layer. Silicon vias are etched in the silicon capping layer, and a redistribution layer process is applied to connect the silicon vias and the wiring layer. A solder resist layer is disposed on the silicon capping layer; The back side of the substrate is etched to form a pressure-sensitive cavity.

2. The method for fabricating a pressure sensor based on flip-chip bonding as described in claim 1, characterized in that, The wiring layer includes an insulating layer, wiring, and a bonding dielectric layer; The step of setting a wiring layer on the sensitive thin film layer includes: An insulating layer with a second predetermined pattern is deposited on the upper surface of the sensitive thin film layer; a cavity is reserved in the center of the insulating layer; A wiring and bonding dielectric layer are disposed on the insulating layer; the wiring is used to connect the sensitive thin film layer and the silicon capping layer; a cavity is reserved in the center of the silicon capping layer; the bonding dielectric layer is used to bond the insulating layer and the silicon capping layer.

3. The method for fabricating a pressure sensor based on flip-chip bonding as described in claim 1, characterized in that, The height range of the stop structure satisfies the condition that the upper surface of the stop structure is within the maximum movable position range of the sensitive film layer, and is within the movable position range that is less than the Von mise stress of the sensitive film layer.

4. The method for fabricating a pressure sensor based on flip-chip bonding as described in claim 1, characterized in that, After etching through-silicon vias in the silicon capping layer and before depositing a solder resist layer on the silicon capping layer, the fabrication method of the pressure sensor based on flip-chip bonding further includes: Electroplating is performed on the silicon vias within the silicon capping layer to form a metal layer; A dielectric layer with a third preset pattern is formed on the metal layer and the silicon capping layer.

5. The method for fabricating a pressure sensor based on flip-chip bonding as described in claim 1, characterized in that, The step of forming a sensitive thin film layer on the oxide layer includes: A sensitive thin film is grown on the oxide layer; A groove of a first preset pattern is etched on the sensitive thin film; The varistor is placed in the groove of the first preset pattern to form a sensitive thin film layer.

6. The method for fabricating a pressure sensor based on flip-chip bonding as described in claim 1, characterized in that, Also includes: A dedicated grounding hole is designed to connect the inversion layer and the silicon capping layer of the substrate.

7. The method for fabricating a pressure sensor based on flip-chip bonding as described in claim 1, characterized in that, The oxide layer is grounded.

8. The method for fabricating a pressure sensor based on flip-chip bonding as described in claim 1, characterized in that, The internal pressure of the enclosed cavity structure is less than one atmosphere.

9. A pressure sensor based on flip-chip bonding technology, characterized in that, The pressure sensor is a dynamic pressure sensor, which is fabricated using the pressure sensor fabrication method based on flip-chip bonding process as described in any one of claims 1 to 8, and includes, from bottom to top, a substrate, an oxide layer, a sensitive thin film layer, a wiring layer, a silicon capping layer, and a solder resist layer. The sensitive thin film layer is provided with a piezoresistor; the cavity of the silicon capping layer is provided with stop structures of different heights and positions; the silicon capping layer, the sensitive thin film layer, and the wiring layer form a closed cavity structure; the stop structures are surrounded within the closed cavity structure; a through-silicon via is provided within the silicon capping layer, and the through-silicon via is connected to the wiring layer; a pressure-sensitive cavity is provided on the back side of the substrate.

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