A pressure sensor and a method of manufacturing the same

Abstract

A pressure sensor and its fabrication method are disclosed. The pressure sensor comprises: an SOI substrate consisting of a silicon substrate, an insulating layer, and a thin silicon layer stacked sequentially from bottom to top; a piezoresistive strip embedded in the thin silicon layer, including a first doped region and a second doped region; a dielectric layer located on the thin silicon layer, the dielectric layer having contact holes to expose the first doped region; a first metal structure filling the contact holes for interconnection; a first protective layer located on the dielectric layer and covering the first metal structure; a metal-insulator phase change material layer located on a portion of the surface of the first protective layer; a second protective layer covering the metal-insulator phase change material layer; and a second metal structure serving as a metal interconnect between the first metal structure and the metal-insulator phase change material layer. This invention can improve the accuracy and stability of the pressure sensor by utilizing the characteristics of the metal-insulator phase change material layer.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically to a pressure sensor and its fabrication method. Background Technology

[0002] The core advantage of MEMS pressure sensors lies in their use of semiconductor microfabrication technology, which enables miniaturization, low cost, and high reliability. Their extremely small size and light weight facilitate easy integration into space, leading to their widespread application. However, MEMS pressure sensors are highly sensitive to their operating environment; extreme temperatures, strong electromagnetic interference, or contact with certain corrosive media can all affect their performance or even cause failure. Furthermore, the device's raw output signal is weak and susceptible to temperature drift, requiring complex back-end compensation circuits and calibration algorithms. This increases the complexity of the system design and results in lower accuracy and stability for the pressure sensor. Summary of the Invention

[0003] The technical problem solved by this invention is to provide a pressure sensor and its fabrication method, which uses a vanadium oxide layer to prepare a vanadium oxide layer on top of a varistor to provide real-time feedback of the varistor temperature for processing by a compensation circuit, thereby improving the accuracy and stability of the pressure sensor.

[0004] To address the aforementioned technical problems, the present invention provides a pressure sensor comprising: an SOI substrate, the SOI substrate comprising a silicon substrate, an insulating layer, and a thin silicon layer stacked sequentially from bottom to top; a piezoresistive strip embedded in the thin silicon layer and exposed on the top surface of the thin silicon layer, the piezoresistive strip comprising a first doped region and a second doped region; a dielectric layer located on the thin silicon layer, the dielectric layer having contact holes to expose the second doped region; a first metal structure filling the contact holes for interconnection; a first protective layer located on the dielectric layer and covering the first metal structure; a metal-insulator phase change material layer located on a portion of the surface of the first protective layer; a second protective layer covering the metal-insulator phase change material layer; and a second metal structure serving as a metal interconnect between the first metal structure and the metal-insulator phase change material layer.

[0005] Optionally, the material of the metal insulator phase change material layer is vanadium oxide.

[0006] Optionally, the projection of the first doped region onto the surface of the SOI substrate is located within the range of the projection of the metal-insulator phase change material layer onto the surface of the SOI substrate.

[0007] Optionally, the pressure sensor further includes: a first conductive opening that penetrates the first protective layer and the second protective layer and exposes the surface of the first metal structure; a second conductive opening that penetrates the second protective layer and exposes the surface of the metal insulator phase change material layer, wherein the second metal structure is located within the first conductive opening and the second conductive opening.

[0008] Optionally, the pressure sensor further includes: a cavity that penetrates the silicon substrate and exposes the surface of the insulating layer, wherein the projection of the piezoresistive strip on the surface of the silicon substrate is located within the cavity.

[0009] Accordingly, the present invention also provides a method for fabricating a pressure sensor, comprising: providing an SOI substrate, the SOI substrate comprising a silicon substrate, an insulating layer, and a thin silicon layer stacked sequentially from bottom to top; forming a piezoresistive strip within the thin silicon layer, the piezoresistive strip being exposed on the top surface of the thin silicon layer, the piezoresistive strip comprising a first doped region and a second doped region; forming a dielectric layer on the thin silicon layer; forming a contact hole within the dielectric layer to expose the second doped region; filling the contact hole with a first metal structure, the first metal structure being used for interconnection; forming a first protective layer on the dielectric layer, the first protective layer covering the first metal structure; and so on. A metal-insulator phase change material layer is formed on a portion of the surface of the first protective layer; a second protective layer is formed on the surface of the metal-insulator phase change material layer; a first conductive opening is formed through the first and second protective layers, exposing the surface of the first metal structure; a second conductive opening is formed through the second protective layer, exposing the surface of the metal-insulator phase change material layer; a second metal structure is formed within the first and second conductive openings, the second metal structure serving as a metal connection between the first metal structure and the metal-insulator phase change material layer; and a cavity is formed within the silicon substrate.

[0010] Optionally, the method for fabricating the pressure sensor further includes: the cavity penetrating the silicon substrate and exposing the surface of the insulating layer, wherein the projection of the piezoresistive strip on the surface of the silicon substrate is located within the cavity.

[0011] Optionally, the method for fabricating the pressure sensor further includes: thinning the SOI substrate before forming the cavity.

[0012] Optionally, the first doped region is formed using an ion implantation process with an implantation dose of 5e14 per square centimeter to 3e15 per square centimeter; and the second doped region is formed using an ion implantation process with an implantation dose of 3e15 per square centimeter to 1e16 per square centimeter.

[0013] Optionally, the method of forming the first metal structure includes: depositing a first metal in the contact hole and on the surface of the dielectric layer, etching the first metal, forming the first metal structure in the contact hole and on a portion of the surface of the dielectric layer, wherein the top surface of the first metal structure is higher than the surface of the dielectric layer.

[0014] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: The pressure sensor provided by this invention includes an SOI substrate composed of a silicon substrate, an insulating layer, and a thin silicon layer stacked sequentially from top to bottom. A piezoresistive strip, comprising a first doped region and a second doped region, is embedded within the thin silicon layer and exposed on its top surface. A dielectric layer is disposed on the thin silicon layer, and contact holes within the dielectric layer expose the second doped region. Simultaneously, a first metal structure for interconnection fills the contact holes. Therefore, the current in the piezoresistive strip can be drawn out by the first metal structure. Since a first protective layer is located on the dielectric layer and covers the first metal structure, and a metal-insulator phase change material layer is located on a portion of the surface of the first protective layer, and because the metal-insulator phase change material has a high absolute value of negative temperature coefficient of resistance (TCR) below its phase change temperature, its resistance drops sharply when a phase change occurs. Therefore, the metal-insulator phase change material can be used as a thermistor to measure temperature. Because the second protective layer covers the metal-insulator phase change material layer, and the second metal structure connects the first metal structure and the metal-insulator phase change material layer respectively, the current in the metal-insulator phase change material layer is drawn out through the second metal structure. Due to the structural relationship of the metal-insulator phase change material layer being located on the piezoresistive strip, the temperature of the varistor can be fed back in real time by the resistance change of the metal-insulator phase change material layer, and this information is provided to the processing circuit to compensate for the output drift of the varistor caused by temperature changes in real time. This simplifies the back-end compensation circuit and calibration algorithm, thereby improving the accuracy and stability of the pressure sensor. Furthermore, because the second protective layer covers the metal-insulator phase change material layer, it can prevent the metal-insulator phase change material layer from coming into contact with oxygen and causing electrical changes, thereby improving the accuracy of using the metal-insulator phase change material as a thermistor to measure temperature, further improving the accuracy and stability of the pressure sensor.

[0015] Furthermore, since the cavity penetrates the bottom silicon substrate and exposes the surface of the insulating layer, the projection of the piezoresistive strip on the surface of the silicon substrate is located within the cavity. Therefore, the heat preservation effect brought about by the cavity further improves the accuracy of the real-time feedback of the temperature of the piezoresistor through the resistance change of the metal insulator phase change material layer, thereby improving the accuracy and stability of the pressure sensor.

[0016] The method for preparing the pressure sensor provided by the technical solution of the present invention is used to prepare the pressure sensor described above, and therefore also has the technical effects of the pressure sensor described above, which will not be repeated here. Attached Figure Description

[0017] Figures 1 to 11 This is a schematic diagram of the structure of each step in the preparation method of the pressure sensor according to an embodiment of the present invention.

[0018] Explanation of reference numerals in the attached figures: 100, SOI substrate; 103, silicon substrate; 102, insulating layer; 101, thin silicon layer; 110, first doped region; 120, second doped region; 130, piezoresistive strip; 104, cavity; 200, Dielectric layer; 201, Contact hole; 210, First metal structure; 300, First protective layer; 400, Metal-insulator phase change material layer; 500, Second protective layer; 610, First conductive opening; 620, Second conductive opening; 630, Second metal structure. Detailed Implementation

[0019] As described in the background section, the raw output signal of MEMS pressure sensors is weak and susceptible to temperature drift, requiring complex back-end compensation circuits and calibration algorithms, resulting in poor accuracy and stability of the pressure sensors.

[0020] The primary cause of temperature drift in MEMS pressure sensors lies in the changing physical properties of silicon, their core material. First, the piezoresistive element, acting as the sensing element, exhibits temperature sensitivity; its resistance changes with increasing temperature, resulting in a signal shift independent of pressure. Simultaneously, the differences in thermal expansion coefficients between silicon and other materials within the sensor (such as silicon, glass, and metal) generate additional thermal stress with temperature changes, which the piezoresistive structure may mistakenly detect as pressure signals. Furthermore, the properties of the measured medium (such as viscosity) also affect pressure transmission with temperature variations. The combined effect of these physical factors causes the sensor's output signal to drift with operating temperature, requiring hardware compensation or software algorithms to ensure measurement accuracy across the entire temperature range.

[0021] To address the aforementioned technical problems, the present invention provides a pressure sensor and its fabrication method. By fabricating a vanadium oxide layer above a varistor, the temperature of the varistor is fed back in real time for processing by a compensation circuit, thereby simplifying circuit design and improving the accuracy and stability of the pressure sensor.

[0022] To make the above-mentioned objectives, features, and beneficial effects of the present invention more apparent and understandable, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus. Additionally, directional terms such as above, below, up, down, upward, downward, left, right, etc., are used relative to exemplary embodiments as they are shown in the figures, with upward or upper directions pointing towards the top of the corresponding figure and downward or lower directions pointing towards the bottom of the corresponding figure.

[0024] Figures 1 to 11 This is a schematic diagram of the structure of each step in the preparation method of the pressure sensor according to an embodiment of the present invention.

[0025] Please refer to Figure 1 SOI substrate 100 is provided.

[0026] In this embodiment, the SOI substrate 100 includes a silicon substrate 103, an insulating layer 102, and a thin silicon layer 101 stacked sequentially from bottom to top. The SOI substrate 100 may also include at least one of the following materials: Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP, InGaAs, or other III / V compound semiconductors. Alternatively, the SOI substrate 100 may also include a silicon substrate, silicon-on-insulator (SSOI), silicon-on-insulator (S-SiGeOI), silicon-on-insulator (SiGeOI), or germanium-on-insulator (GeOI), etc. The size of the substrate 100 can be 6 inches, 8 inches, 12 inches, etc., and is not limited thereto.

[0027] Specifically, the thickness of the insulating layer 102 can be 0.5μm to 1μm.

[0028] Specifically, the thickness of the thin silicon layer 101 can be 5μm to 15μm.

[0029] Please refer to Figure 2 and Figure 3 A piezoresistive strip 130 is formed within a thin silicon layer 101. The piezoresistive strip 130 includes a first doped region 110 and a second doped region 120.

[0030] Please continue to refer to this. Figure 2 The method for forming the first doped region 110 may include: forming a first mask (not shown) on the surface of a thin silicon layer 101, performing ion implantation using the first mask as a mask, removing the first mask, and forming the first doped region 110.

[0031] In this embodiment, the implantation dose of the first doped region 110 is 5e14 per square centimeter to 3e15 per square centimeter.

[0032] Please refer to Figure 3 A second doped region 120 is formed within the thin silicon layer 101.

[0033] The second doped region 120 is located on both sides of the first doped region 110, and the doping concentration of the first doped region 110 is lower than that of the second doped region 120.

[0034] In this embodiment, the implantation dose of the second doped region 120 is 3e15 per square centimeter to 1e16 per square centimeter.

[0035] Specifically, the method for forming the second doped region 120 includes: forming a second mask (not shown) on the surface of the thin silicon layer 101, performing ion implantation using the second mask as a mask, removing the second mask, and forming the second doped region 120.

[0036] Please refer to Figure 4 A dielectric layer 200 is formed on a thin silicon layer 101, and a contact hole 201 is formed in the dielectric layer 200 to expose the second doped region 120.

[0037] In this embodiment, the dielectric layer 200 can be made of silicon dioxide.

[0038] Specifically, the method for forming dielectric layer 200 may include: forming an initial dielectric layer (not shown) on the surface of thin silicon layer 101, the surface of first doped region 110, and the surface of second doped region 120; etching the initial dielectric layer to form contact hole 201 and dielectric layer 200, wherein the contact hole 201 penetrates the initial dielectric layer and exposes the surface of first doped region 110.

[0039] Please refer to Figure 5 The first metal structure 210 is filled into the contact hole 201.

[0040] In this embodiment, the first metal structure 210 is used for wiring.

[0041] In this embodiment, the top surface of the first metal structure 210 is higher than the surface of the dielectric layer 200.

[0042] In this embodiment, the material of the first metal structure 210 may include aluminum.

[0043] Specifically, the method for forming the first metal structure 210 may include: forming an initial first conductive layer (not shown) in the contact hole 201 and on the surface of the dielectric layer 200, etching the initial first conductive layer, and forming the first metal structure 210.

[0044] Please refer to Figure 6 A first protective layer 300 is formed on the dielectric layer 200.

[0045] In this embodiment, the first protective layer 300 covers the first metal structure 210.

[0046] In this embodiment, the material of the first protective layer 300 may include silicon nitride.

[0047] Specifically, the method for forming the first protective layer 300 may include depositing the first protective layer 300 on the surface of the dielectric layer 200 and the surface of the first metal structure 210.

[0048] Please refer to Figure 7 A metal insulator phase change material layer 400 is formed on the surface of a portion of the first protective layer 300.

[0049] The projection of the first doped region 110 onto the surface of the SOI substrate 100 is located within the range of the projection of the metal-insulator phase change material layer 400 onto the surface of the SOI substrate 100.

[0050] Specifically, the method for forming the metal-insulator phase change material layer 400 may include: forming an initial metal-insulator phase change material layer (not shown) on the surface of the first protective layer 300, etching the initial metal-insulator phase change material layer, and forming the metal-insulator phase change material layer 400.

[0051] Please refer to Figure 8 A second protective layer 500 is formed on the surface of the metal insulator phase change material layer 400.

[0052] Specifically, the material of the second protective layer 500 can be silicon nitride.

[0053] Please refer to Figure 9 A first conductive opening 610 is formed by penetrating the first protective layer 300 and the second protective layer 500, and a second conductive opening 620 is formed by penetrating the second protective layer 500.

[0054] The first conductive opening exposes the surface of the first metal structure 210, and the second conductive opening 620 exposes the surface of the metal insulator phase change material layer 400.

[0055] Specifically, the method for forming the first conductive opening 610 and the second conductive opening 620 may include: etching the first protective layer 300 and the second protective layer 500 on the first metal structure 210, and the first protective layer 300 on the metal insulator phase change material layer 400, until the first conductive opening 610 exposed on the surface of the first metal structure 210 and the second conductive opening 620 exposed on the surface of the metal insulator phase change material layer 400 are formed.

[0056] Specifically, there are two second conductive openings 620, located at both ends of the metal insulator phase change material layer 400.

[0057] Please refer to Figure 10 A second metal structure 630 is formed within the first conductive opening 610 and the second conductive opening 620.

[0058] In this embodiment, the second metal structure 630 serves as a metal connection between the first metal structure 210 and the metal insulator phase change material layer 400.

[0059] In this embodiment, the second metal structure 630 is a metal stack structure, which includes a titanium layer and a titanium nitride layer located on the surface of the titanium layer.

[0060] Specifically, the method for forming the second metal structure 630 includes: depositing a monolayer Ti / TiN metal film within the first conductive opening 610, the second conductive opening 620, and on the surface of the second protective layer 500; etching the metal to form the second metal structure 630 located within the first conductive opening 610 and the second conductive opening 620. The monolayer Ti / TiN metal film deposited within the first conductive opening 610 and the monolayer Ti / TiN metal film deposited within an adjacent second conductive opening 620 serve as a metal interconnect. This metal interconnect is used to transmit electrical signals to an external signal processing circuit, ultimately enabling signal reading and control.

[0061] Please refer to Figure 11 A cavity 104 is formed within the silicon substrate 103.

[0062] The cavity 104 penetrates the silicon substrate 103 and exposes the surface of the insulating layer 102, and the projection of the piezoresistive strip 130 on the surface of the silicon substrate 103 is located within the cavity 104.

[0063] In this embodiment, the method for forming the cavity 104 may include deep silicon etching.

[0064] In this embodiment, the SOI substrate 100 can also be thinned before the cavity 104 is formed.

[0065] In this embodiment, the pressure sensor is fabricated by first forming an SOI substrate 100 consisting of a silicon substrate 103, an insulating layer 102, and a thin silicon layer 101 stacked sequentially from top to bottom. A piezoresistive strip 130, including a first doped region 110 and a second doped region 120, is embedded within the thin silicon layer and exposed on the top surface of the thin silicon layer 101. Since a dielectric layer 200 is disposed on the thin silicon layer 101, and the dielectric layer 200 has contact holes 201 that expose the second doped region 120, and a first metal structure 210 for interconnection fills the contact holes 201, the current in the piezoresistive strip 130 can be drawn out by the first metal structure 210. Since the first protective layer 300 is located on the dielectric layer 200 and covers the first metal structure 210, and the metal-insulator phase change material layer 400 is located on part of the surface of the first protective layer 300, and since the metal-insulator phase change material has a high absolute value of negative temperature coefficient of resistance (TCR) below the phase change temperature, its resistance will drop sharply when the metal-insulator phase change material undergoes a phase change, therefore, the metal-insulator phase change material can be used as a thermistor to measure temperature. Since the second protective layer 500 covers the metal-insulator phase change material layer 400, and the second metal structure 630 serves as a metal connection between the first metal structure 210 and the metal-insulator phase change material layer 400, the current of the metal-insulator phase change material layer 400 is led out by the second metal structure 630, and the metal connection is used to transmit electrical signals to external signal processing circuits, ultimately realizing signal reading and control. Due to the structural relationship of the metal-insulator phase change material layer 400 located on the piezoresistive strip 130, the temperature of the varistor can be fed back in real time by the resistance change of the metal-insulator phase change material layer 400. This feedback is then provided to the processing circuit to compensate for the output drift of the varistor caused by temperature changes, thereby simplifying the back-end compensation circuit and calibration algorithm, and ultimately improving the accuracy and stability of the pressure sensor. Furthermore, since the second protective layer 500 covers the metal-insulator phase change material layer 400, it prevents the metal-insulator phase change material layer 400 from contacting oxygen and causing electrical changes. This further improves the accuracy of using the metal-insulator phase change material as a thermistor for temperature measurement, and further enhances the accuracy and stability of the pressure sensor. Furthermore, since the cavity 104 penetrates the silicon substrate 103 and exposes the surface of the insulating layer 102, the projection of the piezoresistive strip 130 on the surface of the silicon substrate 103 is located within the cavity 104. Therefore, the heat preservation effect brought about by the cavity 104 further improves the accuracy of the temperature feedback of the piezoresistive resistor in real time through the resistance change of the metal insulator phase change material layer 400, thereby improving the accuracy and stability of the pressure sensor.

[0066] Accordingly, this embodiment of the invention also provides a pressure sensor prepared based on the above-described method for preparing a pressure sensor.

[0067] Please continue to refer to this. Figure 11 The pressure sensor includes: an SOI substrate 100, a piezoresistive strip 130, a dielectric layer 200, a first metal structure 210, a first protective layer 300, a metal-insulator phase change material layer 400, a second protective layer 500, and a second metal structure 630.

[0068] The substrate 100 includes a silicon substrate 103, an insulating layer 102 and a thin silicon layer 101 stacked from bottom to top.

[0069] Piezoresistive strip 130 is embedded in thin silicon layer 101 and exposed on top surface of thin silicon layer 101. Piezoresistive strip 130 includes first doped region 110 and second doped region 120.

[0070] The dielectric layer 200 is located on the thin silicon layer 101, and the dielectric layer 200 has contact holes 201 to expose the second doped region 120.

[0071] The first metal structure 210 fills the contact hole 201 and is used for wiring.

[0072] The first protective layer 300 is located on the dielectric layer 200 and covers the first metal structure 210.

[0073] The metal insulator phase change material layer 400 is located on part of the surface of the first protective layer 300.

[0074] The second protective layer 500 covers the metal insulator phase change material layer 400.

[0075] The second metal structure 630 serves as a metal connection between the first metal structure 210 and the metal insulator phase change material layer 400.

[0076] Furthermore, the silicon substrate 103 also includes a cavity 104, and the projection of the piezoresistive strip 130 on the surface of the silicon substrate 103 is located within the cavity 104.

[0077] Specifically, the materials, forming process, working principle, specific implementation method and beneficial effects of the pressure sensor in the embodiments of the present invention can be found in the preparation method of the pressure sensor in the embodiments of the present invention, and will not be repeated here.

[0078] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A pressure sensor, characterized in that, include: SOI substrate, the SOI substrate comprising a silicon substrate, an insulating layer and a thin silicon layer stacked sequentially from bottom to top; A piezoresistive strip is embedded in the thin silicon layer and exposed on the top surface of the thin silicon layer. The piezoresistive strip includes a first doped region and a second doped region. A dielectric layer is located on the thin silicon layer, and the dielectric layer has contact holes to expose the second doped region; A first metal structure is filled in the contact hole for wiring; A first protective layer is located on the dielectric layer and covers the first metal structure; A metal-insulator phase change material layer is located on a portion of the surface of the first protective layer; A second protective layer covers the metal insulator phase change material layer. A second metal structure serves as a metal connection between the first metal structure and the metal insulator phase change material layer.

2. The pressure sensor as described in claim 1, characterized in that, The material of the metal insulator phase change material layer is vanadium oxide.

3. The pressure sensor as described in claim 2, characterized in that, The projection of the first doped region onto the surface of the SOI substrate is within the range of the projection of the metal-insulator phase change material layer onto the surface of the SOI substrate.

4. The pressure sensor as described in claim 1, characterized in that, Also includes: A first conductive opening penetrates the first protective layer and the second protective layer, and exposes the surface of the first metal structure; The second conductive opening penetrates the second protective layer and exposes the surface of the metal insulator phase change material layer. The second metal structure is located within the first conductive opening and the second conductive opening.

5. The pressure sensor as described in claim 1, characterized in that, Also includes: A cavity that penetrates the silicon substrate and exposes the surface of the insulating layer, wherein the projection of the piezoresistive strip on the surface of the silicon substrate is located within the cavity.

6. A method for manufacturing a pressure sensor, characterized in that, include: An SOI substrate is provided, the SOI substrate comprising a silicon substrate, an insulating layer and a thin silicon layer stacked sequentially from bottom to top; A piezoresistive strip is formed within the thin silicon layer, the piezoresistive strip being exposed on the top surface of the thin silicon layer, and the piezoresistive strip includes a first doped region and a second doped region. A dielectric layer is formed on the thin silicon layer; A contact hole is formed within the dielectric layer to expose the second doped region. A first metal structure is filled into the contact hole, and the first metal structure is used for wiring. A first protective layer is formed on the dielectric layer, and the first protective layer covers the first metal structure; A metal insulator phase change material layer is formed on the surface of the first protective layer portion; A second protective layer is formed on the surface of the metal insulator phase change material layer; A first conductive opening is formed through the first protective layer and the second protective layer, exposing the surface of the first metal structure; a second conductive opening is formed through the second protective layer, exposing the surface of the metal insulator phase change material layer. A second metal structure is formed within the first conductive opening and the second conductive opening, and the second metal structure serves as a metal connection between the first metal structure and the metal insulator phase change material layer. A cavity is formed within the silicon substrate.

7. The method for preparing a pressure sensor as described in claim 6, characterized in that, Also includes: The cavity penetrates the silicon substrate and exposes the surface of the insulating layer, and the projection of the piezoresistive strip on the surface of the silicon substrate is located within the cavity.

8. The method for preparing a pressure sensor as described in claim 7, characterized in that, Also includes: The SOI substrate is thinned before the cavity is formed.

9. The method for manufacturing a pressure sensor as described in claim 6, characterized in that, The first doped region is formed using an ion implantation process with an implantation dose of 5e14 to 3e15 per square centimeter; the second doped region is formed using an ion implantation process with an implantation dose of 3e15 to 1e16 per square centimeter.

10. The method for preparing a pressure sensor as described in claim 6, characterized in that, The method of forming the first metal structure includes: depositing a first metal in the contact hole and on the surface of the dielectric layer, etching the first metal, forming the first metal structure in the contact hole and on a portion of the surface of the dielectric layer, wherein the top surface of the first metal structure is higher than the surface of the dielectric layer.

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