A piezoresistive pressure sensor

Abstract

This application relates to the field of sensing technology, specifically providing a piezoresistive pressure sensor, which includes a silicon substrate and metal leads. A recessed structure is formed on one side of the silicon substrate, and a silicon diaphragm is formed at the bottom of the recessed structure. An ultra-shallow doped region is formed on the surface of the silicon diaphragm away from the recessed structure. The metal leads are fixedly disposed on the side of the silicon substrate away from the recessed structure, with at least one end of the metal leads in fixed contact with the ultra-shallow doped region. The ultra-shallow doped region is connected to an electrical circuit via the metal leads. The metal leads are fabricated using magnetron sputtering or deposition. The ultra-shallow doped region is fabricated using a low-energy ion implantation process. The recessed structure is fabricated using a time-division multiplexing etching technique. In this invention, the doping thickness of the ultra-shallow doped region is on the nanometer scale, which allows for a large change in resistance even with small deformation in a micro-pressure environment, thereby achieving highly sensitive detection of micro-pressures.

Description

Technical Field

[0001] This application relates to the field of sensing technology, and more specifically, to a piezoresistive pressure sensor. Background Technology

[0002] A pressure sensor is a device that converts changes in the mechanical physical quantity of pressure into the movement of a pointer or an electrical physical quantity, making pressure changes that are difficult to detect detectable. Depending on the type of electrical physical quantity converted, common pressure sensors include capacitive pressure sensors and piezoresistive pressure sensors. Changes in pressure cause changes in capacitance and resistance, respectively. By directly or indirectly detecting these changes in capacitance and resistance, the pressure change can be obtained. Piezoresistive pressure sensors are more common and have a higher market share.

[0003] When the pressure to be measured is high, the large pressure acts on the piezoresistive pressure sensor, causing significant deformation of the sensor diaphragm during detection. This results in a strong piezoresistive effect, a large change in resistance, and a high output value with high sensitivity. However, in fields such as medical sensing, industrial inspection, and aerospace, where sensing of lower pressures is required, the piezoresistive pressure sensor exhibits very low diaphragm deformation and stress in low-pressure environments. This leads to a weak piezoresistive effect, resulting in low output and low sensitivity, which fails to meet sensing requirements. The low sensitivity of low-pressure sensing leads to distorted sensing results, causing misjudgments and malfunctions in the application equipment.

[0004] Existing piezoresistive pressure sensors improve sensitivity by changing their structure, such as amplifying deformation caused by minute pressure through complex structures. This increases the difficulty of the manufacturing process, resulting in poor consistency and low yield of the fabricated piezoresistive pressure sensors, which is not conducive to industrial mass production; and the sensitivity is still relatively low.

[0005] In summary, existing piezoresistive pressure sensors cannot meet the high sensitivity requirements for sensing minute pressures and are not easy to mass-produce in industry. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of the prior art by providing a piezoresistive pressure sensor. The technical concept of this invention is to limit the thickness of the resistor to the nanometer scale, specifically, the doping thickness of the ultra-shallow doped region is on the nanometer scale. This amplifies the piezoresistive effect, allowing even small deformations to cause significant changes in resistance.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] This application provides a piezoresistive pressure sensor, which includes a silicon substrate and metal leads. The silicon substrate is made of SOI (Silicon-On-Insulator) silicon wafer, and the metal leads are made of metal, utilizing the conductivity of the metal to connect the electrical circuit. The silicon substrate is rectangular or flattened cylindrical in shape; preferably, it is rectangular, which facilitates fabrication and integration. A recessed structure is provided on one side of the silicon substrate. The bottom surface of the recessed structure can be rectangular or circular; preferably, the depth of the recessed structure is uniform and the bottom surface is rectangular. The recessed structure is fabricated using a time-division multiplexing etching technique.

[0009] A silicon film is formed at the bottom of the recessed structure. The shape of the silicon film is the same as the bottom shape of the recessed structure, preferably rectangular. Its thickness is on the order of micrometers, allowing for easy deformation. An ultra-shallow doped region is formed on the surface of the silicon film away from the recessed structure. The doping depth of the ultra-shallow doped region is on the order of nanometers. The doping ions in the ultra-shallow doped region are boron ions or phosphorus ions; specifically, the types of doping ions can be the same or different, preferably the types of doping ions in the ultra-shallow doped region are the same. The ultra-shallow doped region is fabricated using a low-energy ion implantation process. The shape of the metal leads can be arbitrary, such as strips, sheets, or rods. The metal leads are prepared using magnetron sputtering or deposition. The metal leads are fixedly disposed on the side of the silicon substrate away from the recessed structure. The ultra-shallow doped regions are connected by the metal leads to form an electrical circuit to detect the resistance change in the ultra-shallow doped regions. The electrical circuit includes at least necessary circuit components such as a power supply, switch, voltmeter, and ammeter, capable of resistance detection, such as the voltmeter-ammeter method for resistance measurement.

[0010] Furthermore, there are four ultra-shallow doped regions, preferably arranged in the following direction: <110> Four ultra-shallow doped regions are distributed in the stress concentration area of ​​the silicon film. These four ultra-shallow doped regions act as four resistors, connected by metal leads to form a Wheatstone bridge, which is used to detect changes in resistance. The Wheatstone bridge can sensitively detect changes in resistance.

[0011] Furthermore, while the aforementioned pressure sensor is a gauge pressure sensor, this invention also discloses an absolute pressure sensor. Specifically, a glass plate is fixedly disposed on the side of the recessed structure away from the ultra-shallow doped region, forming a cavity between the glass plate and the recessed structure. The glass plate and the silicon substrate on the side with the recessed structure are fixedly connected by bonding. Specifically, anodic bonding technology is used to bond the glass plate and the silicon wafer together to form a vacuum cavity. The specific vacuum level is related to the bonding process. In this way, a constant pressure is formed on the side of the silicon diaphragm near the glass plate. When the pressure on the side of the silicon diaphragm away from the glass plate changes, the silicon diaphragm plate deforms, causing deformation of the ultra-shallow doped region on it. Due to the piezoresistive effect, the resistance of the ultra-shallow doped region changes. The change in the measured pressure is obtained by detecting the change in resistance. Both sides of the gauge pressure sensor are exposed to the measured environment, while only the side of the silicon diaphragm away from the recessed structure is exposed to the measured environment in the absolute pressure sensor. Therefore, the gauge pressure sensor is suitable for detecting pressure changes caused by the pressure difference between the two sides, while the absolute pressure sensor is suitable for environments with unilateral pressure changes.

[0012] Compared with existing technologies, the beneficial effects of this invention are as follows: The doping thickness of the ultra-shallow doped region in this invention is on the order of nanometers. Thus, under the same degree of deformation, the small thickness can induce a large change in resistance. That is, even with small deformation in a micro-pressure environment, a large change in resistance value can still be induced, thereby achieving highly sensitive detection of micro-pressure. Furthermore, this invention has a simple structure, is easy to fabricate, and is readily mass-produced industrially. Attached Figure Description

[0013] Figure 1 A front view (ultra-shallow doped region side) of a piezoresistive pressure sensor provided by the present invention;

[0014] Figure 2 Rear view (recessed structure side) of a piezoresistive pressure sensor provided by the present invention;

[0015] Figure 3 This is a schematic diagram of an ultra-shallow doped region in a piezoresistive pressure sensor provided by the present invention;

[0016] Figure 4 The simulation results of stress distribution of silicon diaphragm in a piezoresistive pressure sensor provided by the present invention;

[0017] Figure 5 This is a schematic diagram of another piezoresistive pressure sensor provided by the present invention.

[0018] Icons: 1-Silicon substrate; 11-Recessed structure; 12-Ultra-shallow doped region; 2-Metal lead. Detailed Implementation

[0019] To make the implementation process of this invention clearer, a detailed description will be provided below in conjunction with the accompanying drawings.

[0020] This invention provides a piezoresistive pressure sensor, such as... Figure 1 and Figure 2 As shown, the pressure sensor includes a silicon substrate 1 and metal leads 2. The silicon substrate 1 is made of SOI (Silicon-On-Insulator) silicon wafer, and the metal leads 2 are made of a metal material. Preferably, the metal leads 2 are made of Ti, Cr, or Au, utilizing the conductivity of the metal to connect the electrical circuit. The silicon substrate 1 is rectangular or flattened cylindrical in shape. Preferably, the silicon substrate 1 is rectangular, which facilitates fabrication and integration. Specifically, the thickness of the silicon substrate 1 is 200-600 μm. A recessed structure 11 is provided on one side of the silicon substrate 1. The bottom surface of the recessed structure 11 can be rectangular or circular. Preferably, the depth of the recessed structure 11 is uniform and the bottom surface is rectangular. Specifically, the bottom surface can be a square with equal side lengths or a rectangle. The depth of the recessed structure 11 can be uniform or non-uniform. Preferably, the depth of the recessed structure 11 is uniform, so that the base of the thickness change caused by deformation is the same, making the change in resistance easier to detect. Otherwise, some positions have higher sensitivity and some positions have lower sensitivity, which will affect each other and reduce the detection sensitivity of the resistance change. The specific size of the recessed structure 11 is related to the range of the pressure sensor. The recessed structure 11 is prepared using a time-division multiplexing etching technique. Specifically, the recessed structure 11 is formed by etching the silicon substrate 1, with passivation protection and etching alternating.

[0021] A silicon film is formed at the bottom of the recessed structure 11. The shape of the silicon film is the same as the bottom surface shape of the recessed structure; preferably, the silicon film is rectangular or circular. The thickness of the silicon film is on the order of micrometers. Preferably, the thickness of the silicon film needs to conform to the small deflection theory, so that the stress change of the silicon film remains linear when the maximum range is reached. An ultra-shallow doped region 12 is formed on the surface of the silicon film away from the recessed structure 11. The doping depth of the ultra-shallow doped region 12 is on the order of nanometers, specifically, the doping depth is 10-30 nm, preferably 20 nm. The doping ions of the ultra-shallow doped region 12 are boron ions or phosphorus ions. More specifically, the types of doping ions can be the same or different. Preferably, the types of doping ions in the ultra-shallow doped region 12 are the same, which facilitates preparation and avoids uneven resistance changes caused by different ion types. Thus, the resistance change of the ultra-shallow doped region 12 is only related to deformation, improving sensing sensitivity and accuracy. After doping, the dopant ions increase the conductivity of the semiconductor, transforming the insulating ultra-shallow doped region 12 from an insulator into a P-type resistor. This is also the resistor used in this invention to detect pressure using the piezoresistive effect. The ultra-shallow doped region 12 is manufactured using a low-energy ion implantation process. Specifically, after the ion beam strikes the solid material, its velocity gradually decreases due to the resistance of the solid material, and it eventually remains in the solid material, thus achieving ion implantation.

[0022] Metal leads 2 are fixedly disposed on the side of the silicon substrate 1 away from the recessed structure 11. Metal leads 2 connect the ultra-shallow doped region 12 to an electrical circuit for detecting resistance changes in the ultra-shallow doped region 12. The electrical circuit includes at least necessary circuit components such as a power supply, switch, voltmeter, and ammeter, capable of resistance detection, such as the voltmeter-ammeter method. The shape of the metal leads 2 can be arbitrary, such as strip, sheet, or rod. The metal leads are fabricated using magnetron sputtering or deposition. During detection, the deformation of the silicon film changes the stress inside the ultra-shallow doped region 12, causing a change in resistance. This change in resistance is detected through the electrical circuit, thus converting a mechanical physical quantity into an electrical physical quantity.

[0023] like Figure 3 As shown, the principle behind the high sensitivity of the pressure sensor when the doping thickness of the ultra-shallow doped region 12 is on the order of nanometers is as follows: For ease of analysis, the resistance of the ultra-shallow doped region 12 is represented by a cuboid, and the expression for the resistance of the ultra-shallow doped region 12 is: Where ρ is the resistivity of the ultra-shallow doped region 12 resistor, L is the length of the ultra-shallow doped region 12 resistor, W is the width of the ultra-shallow doped region 12 resistor, and t is the thickness of the ultra-shallow doped region 12 resistor. Assuming that all parameters except t are fixed, and the deformation of the ultra-shallow doped region 12 is manifested as a change in thickness t, then: in It is a fixed value. Furthermore, the expression for the change in resistance R as the thickness t changes is: Where t1 and t2 are the thicknesses of the ultra-shallow doped region 12 before and after the deformation, respectively. As can be seen above, with a constant change in thickness t, the smaller the thickness t1 before deformation, the greater the change in thickness t1 becomes; that is, the smaller the change in thickness t1 becomes, the greater the change in thickness t1 becomes. The larger the value of ΔR, the larger the pressure sensor's sensitivity. Specifically, assuming the deformation Δt is 50 nm, if the thickness t1 of the ultra-shallow doped region 12 before deformation is 10 nm, then the deformation of t is 5 times the original. If the thickness t1 of the ultra-shallow doped region 12 before deformation is 1000 nm, then the deformation of t is 0.05 times the original. The difference in the amount of change they can cause is huge. Therefore, the pressure sensor of the present invention has high sensitivity, that is, a small deformation can cause a large change in resistance.

[0024] Preferably, the metal lead 2 and the ultra-shallow doped region 12 can be in direct contact, or they can be in contact through an ohmic contact region, such as... Figure 5 As shown, the ultra-shallow doped region 12 is in fixed contact with the ohmic contact region, and the ohmic contact region is in fixed contact with the metal lead 2. This reduces the resistance jump caused by direct contact between the metal lead 2 and the ultra-shallow doped region 12, ensuring circuit continuity. Specifically, the ohmic contact region is obtained through ion implantation and annealing. The type of implanted ions in the ohmic contact region can be the same as or different from the type of implanted ions in the ultra-shallow doped region 12. Preferably, the type of implanted ions in the ohmic contact region is the same as that in the ultra-shallow doped region 12, which facilitates fabrication. The concentration of implanted ions in the ohmic contact region is higher than that in the ultra-shallow doped region 12, thus forming an ohmic contact and ensuring smooth electrical connection.

[0025] Furthermore, four ultra-shallow doped regions 12 are disposed within the stress concentration region, each located at the middle of one side, near the edge. Preferably, the arrangement direction is as follows: <110> The direction of the piezoresistive effect maximizes its coefficient, resulting in a significant piezoresistive effect. Simultaneously, it causes different stress transmission along the straight line containing the two pairs of ultra-shallow doped regions 12, leading to a greater relative change in resistance between the two pairs of ultra-shallow doped regions 12. Stress concentration regions are areas of high stress concentration within the silicon film when it is subjected to deformation. The four ultra-shallow doped regions are distributed within these four stress concentration regions. Specifically, the shape and area of ​​the stress concentration regions are related to the shape and size of the silicon film. Changes in the size of the silicon film do not alter the shape of the stress concentration regions, only their area.

[0026] Figure 4This is a stress distribution diagram of a square silicon diaphragm obtained using finite element method (FEM) simulation. Darker areas represent regions where stress changes are significant and concentrated during deformation; the darker the color, the greater the stress change in the corresponding area during deformation, meaning a larger resistance change occurs in the corresponding area with the ultra-shallow doped region 12. Thus, when the silicon diaphragm deforms, the ultra-shallow doped region 12, located within a stress concentration area, experiences greater deformation and internal stress changes, resulting in a larger resistance change and improved pressure detection sensitivity. Since doping does not alter the stress distribution, the doping area can be clearly defined before doping, and the stress distribution remains unchanged after doping. This ensures that the ultra-shallow doped region 12 has a large deformation range, guaranteeing improved sensitivity and facilitating industrial production. Specifically, the ultra-shallow doped region 12 is located in the middle of the four sides of the silicon diaphragm, near the edge. The distance of the ultra-shallow doped region 12 from the edge is less than one-twentieth of the length of the side. Preferably, the distances of the ultra-shallow doped regions 12 on opposite sides from the edge are the same, while the distances of the ultra-shallow doped regions 12 on adjacent sides from the edge are different. This results in different stress transmission in the two directions of the silicon film, leading to different deformations of the ultra-shallow doped regions 12, i.e., different intensities of the piezoresistive effect, and therefore different degrees of resistance change. More preferably, the silicon film is rectangular in shape, and the distances of the two ultra-shallow doped regions 12 corresponding to the long side from the edge are less than the distances of the two ultra-shallow doped regions 12 corresponding to the short side from the edge. That is, the two ultra-shallow doped regions 12 corresponding to the long side are closer to the edge. Since the stress concentration area corresponding to the long side is closer to the edge and the stress concentration area is more concentrated, the stress change in this area is greater, i.e., the anisotropy of stress transmission in the two directions of the silicon film is greater.

[0027] The four ultra-shallow doped regions 12 are all rectangular in shape. Their shapes can be identical or not. Preferably, opposite sides have identical dimensions. Since the stress concentration areas on opposite sides are symmetrical, identical dimensions on opposite sides maximize the area of ​​the ultra-shallow doped region 12 within the stress concentration area, resulting in a larger resistance change due to deformation and higher sensing sensitivity. Adjacent ultra-shallow doped regions 12 have different shapes, thus satisfying the arrangement direction... <110> While ensuring the orientation, the ultra-shallow doped region 12 is located in the stress concentration area, resulting in a larger relative change in resistance between the two opposite sides during deformation. This means a larger voltage change at the test terminal or a larger current change in the external circuit connected to the test terminal, leading to higher detection sensitivity. The areas of adjacent ultra-shallow doped regions 12 can be equal or unequal. When the areas are equal, the resistance values ​​are equal (when the types and concentrations of doped ions are the same), meaning the Wheatstone bridge changes from balanced to unbalanced during deformation. When the areas are unequal, the resistance values ​​are unequal (when the types and concentrations of doped ions are the same), meaning the Wheatstone bridge becomes even more unbalanced during deformation. More preferably, compared to the two ultra-shallow doped regions 12 corresponding to the short side, the two ultra-shallow doped regions 12 corresponding to the long side are longer and shorter, resulting in a larger relative change in resistance between the two opposite sides during silicon film deformation, thus increasing detection sensitivity. The four ultra-shallow doped regions 12 act as four resistors, connected by metal leads 2 to form a Wheatstone bridge for detecting resistance changes. The Wheatstone bridge can sensitively detect resistance changes. Specifically, in use, the four ends of the metal lead 2 (i.e., as shown) Figure 5 The four corners of the metal leads shown can also be further fitted with larger metal leads to form pins for easy connection between the power supply and test terminals. Any two opposite endpoints are power supply terminals for connecting to the power source, and the other two opposite endpoints are test terminals for connecting to an external test circuit. The external test circuit can measure the voltage between the two test terminals or form a loop to measure the current in the external test circuit; both can reflect the resistance change of the ultra-shallow doped region 12. Specifically, it reflects the relative change in resistance between the two pairs of ultra-shallow doped regions 12. When the resistance values ​​of the four ultra-shallow doped regions 12 are equal, the Wheatstone bridge is balanced, and the voltage at the test terminal is zero. During deformation, the resistance values ​​of the ultra-shallow doped regions 12 on the opposite sides become unequal, meaning the Wheatstone bridge becomes unbalanced, and the voltage at the test terminal is not zero. More specifically, the greater the relative change in resistance between the two pairs of ultra-shallow doped regions 12, that is, the greater the difference in resistance between the two pairs of ultra-shallow doped regions 12, the more unbalanced the Wheatstone bridge, the higher the voltage at the test terminal, and the higher the sensitivity.

[0028] Furthermore, a groove is formed on the outer side of the long side of the silicon film. The length of the groove is longer than the length of the corresponding ultra-shallow doped regions 12 on both sides, and the depth of the groove is greater than 30nm. In this way, the stress transmission in the two directions of the silicon film is more different, which makes the resistance change of the ultra-shallow doped region 12 corresponding to the long side of the silicon film greater. That is, the resistance change of the two pairs of ultra-shallow doped regions 12 is greater, and the difference in resistance change is greater. This makes the Wheatstone bridge more unbalanced, the voltage at the test end is larger, and the change is more obvious, thus the detection sensitivity is higher.

[0029] Furthermore, while the aforementioned pressure sensor is a gauge pressure sensor, this invention also discloses an absolute pressure sensor. Specifically, a glass is fixedly disposed on the side of the recessed structure 11 away from the ultra-shallow doped region 12, forming a cavity between the glass and the recessed structure 11. The glass and the silicon substrate on the side where the recessed structure 11 is disposed are fixedly connected by bonding. Specifically, anodic bonding technology is used to bond the glass and the silicon wafer together to form a vacuum cavity, the vacuum degree inside the vacuum cavity being higher than 5 × 10⁻⁶. -6 The higher the vacuum level, the higher the sensing accuracy. More specifically, the vacuum level is related to the bonding process, which is as follows: The silicon substrate and glass surfaces to be bonded are flattened and cleaned to ensure tight contact. The silicon substrate and glass are sandwiched between two electrodes, with the negative electrode (cathode) in contact with the glass and the positive electrode (anode) in contact with the silicon substrate. A voltage of several hundred to several thousand volts is applied, and the temperature is heated to 752-932°C. Positively charged sodium ions in the glass become mobile and move towards the cathode, leaving a small amount of positive charge near the boundary with the silicon substrate, which is then fixed by electrostatic attraction. Negatively charged oxygen ions from the glass migrate towards the anode and react with silicon upon reaching the boundary to form silicon dioxide; the resulting chemical bonds seal the silicon substrate and glass together, forming a vacuum cavity. In this way, a constant pressure is formed on the side of the silicon diaphragm near the glass. When the pressure on the side of the silicon diaphragm away from the glass changes, the silicon diaphragm deforms, causing deformation of the ultra-shallow doped region 12. Due to the piezoresistive effect, the resistance of the ultra-shallow doped region changes, and the change in the measured pressure is obtained by detecting the change in resistance. Both sides of the gauge pressure sensor are exposed to the measured environment, while only the side of the silicon diaphragm away from the recessed structure 11 is exposed to the measured environment in the absolute pressure sensor. Therefore, gauge pressure sensors are suitable for detecting pressure changes caused by pressure differences between the two sides, while absolute pressure sensors are suitable for pressure detection in closed environments.

[0030] In application, the pressure sensor of this invention is fixed in the pressure environment to be measured, so that the pressure acts on the silicon diaphragm. Under the pressure, the silicon diaphragm deforms, causing the ultra-shallow doped region 12 on it to deform and its thickness to change. According to the piezoresistive effect, the resistance of the ultra-shallow doped region 12 changes. The change in resistance of the ultra-shallow doped region 12 is detected by an electrical circuit, and the change in pressure is obtained by detecting the change in resistance, thus realizing the sensing. The pressure sensor of this invention can be used to detect any type of pressure, such as air pressure, water pressure, etc. In this invention, the doping depth of the ultra-shallow doped region 12 is on the order of nanometers. When the thickness of the ultra-shallow doped region 12 changes, because the initial thickness t1 is small, the change is more noticeable. The value of is relatively large, which makes the change in resistance ΔR of the ultra-shallow doped region 12 larger. That is, the same stress change will make the change in resistance of the ultra-shallow doped region 12 greater, which means that the sensitivity of the pressure sensor located in the small area is high.

[0031] Furthermore, this invention also utilizes a Wheatstone bridge to more sensitively detect changes in resistance. Specifically, deformation results in a greater difference in resistance changes between the two pairs of ultra-shallow doped regions 12, leading to a higher voltage at the test end and improved sensitivity. By enhancing the anisotropy of stress transmission in the silicon diaphragm, the difference in resistance changes between the two pairs of ultra-shallow doped regions 12 is further amplified, thereby enhancing detection sensitivity. Specifically, this invention improves the anisotropy of stress transmission by setting the specific shape and position of the ultra-shallow doped regions 12 and adding grooves, thereby increasing the difference in resistance changes between the two pairs of ultra-shallow doped regions 12 and ultimately improving sensor sensitivity.

[0032] The pressure sensor of this invention can detect changes in range of one-thousandth, for example, in a range of 100 kPa, it can distinguish at least 0.1 kPa. This pressure sensor is not limited to sensing minute pressures; it can be used for any pressure range within its range, specifically depending on the number of integrated components. The advantage of this invention lies in its high sensing sensitivity under minute pressures.

[0033] The above are merely preferred embodiments of the present invention and are not intended to limit the present 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 piezoresistive pressure sensor, characterized in that, The pressure sensor includes a silicon substrate and metal leads. A recessed structure is formed on one side of the silicon substrate, and a silicon diaphragm is formed at the bottom of the recessed structure. An ultra-shallow doped region is formed on the surface of the silicon diaphragm away from the recessed structure. The metal leads are fixedly disposed on the side of the silicon substrate away from the recessed structure. The ultra-shallow doped regions are connected by the metal leads to form an electrical circuit. There are four ultra-shallow doped regions, arranged in a specific direction. <110> The four ultra-shallow doped regions are connected by metal leads to form a Wheatstone bridge. The silicon film is rectangular in shape, and the distance from the edge of the two ultra-shallow doped regions corresponding to the long side is less than the distance from the edge of the two ultra-shallow doped regions corresponding to the short side. A groove is provided on the outer side of the long side of the silicon film, and the length of the groove is longer than the length of the ultra-shallow doped region on the corresponding side.

2. The piezoresistive pressure sensor according to claim 1, characterized in that, The doping depth of the ultra-shallow doped region is on the nanometer scale.

3. The piezoresistive pressure sensor according to claim 2, characterized in that, The doping ions in the ultra-shallow doped region are boron ions or phosphorus ions.

4. The piezoresistive pressure sensor according to claim 3, characterized in that, In the Wheatstone bridge, the two ultra-shallow doped regions on opposite sides have the same doping thickness, while the two ultra-shallow doped regions on adjacent sides have different doping thicknesses.

5. The piezoresistive pressure sensor according to any one of claims 1-4, characterized in that, A glass is fixedly disposed on the side of the recessed structure away from the ultra-shallow doped region, and a cavity is formed between the glass and the recessed structure.

6. The piezoresistive pressure sensor according to claim 5, characterized in that, The glass and the recessed structure are bonded and fixedly connected by anodic bonding technology.

7. The piezoresistive pressure sensor according to claim 1, characterized in that, The metal leads are prepared using magnetron sputtering or deposition.

8. The piezoresistive pressure sensor according to claim 1, characterized in that, The ultra-shallow doped region was fabricated using a low-energy ion implantation process.

9. The piezoresistive pressure sensor according to claim 1, characterized in that, The recessed structure was fabricated using a time-division multiplexing etching technique.

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