Piezoresistive sensor, piezoresistive sensor structure and manufacturing method thereof

Abstract

The invention provides a piezoresistive sensor, a piezoresistive sensor structure and a manufacturing method thereof, the piezoresistive sensor can simulate the magnitude of external pressure borne by the piezoresistive sensor structure by adjusting the voltage difference between two pressure simulation electrodes, and can simulate the magnitude of external pressure borne by the piezoresistive sensor structure by adjusting the driving voltage of the piezoresistive sensor structure. Therefore, the piezoresistive sensor can be used for generating excitation-response pairs required by the PUF technology, so that the PUF key technology can be realized on the piezoresistive sensor. The piezoresistive sensor structure comprises a first substrate and a second substrate arranged below the first substrate, the upper surface of the second substrate is provided with a cavity, and a sensitive film is formed in the first substrate area above the cavity; the Wheatstone bridge structure is arranged on the first substrate; a first pressure simulation electrode is arranged on the surface, facing the cavity, of the sensitive film; and a second pressure simulation electrode is arranged on the surface of the second substrate at the bottom of the cavity.

Description

Technical Field

[0001] The present application relates to the field of sensor technology, and in particular to a piezoresistive sensor, a piezoresistive sensor structure and a manufacturing method thereof. Background Art

[0002] PUF (Physically Unclonable Function) is a security technology based on the physical properties of hardware. It uses the tiny differences naturally occurring during the manufacturing process of the device to generate a unique and difficult-to-copy response to manage the identity of the hardware. The response of each PUF device is unique and cannot be accurately predicted or copied, which makes it important in fields such as the Internet of Things, embedded systems, and cloud computing.

[0003] In the related technology, PUF key technology has been used in some large mobile terminal devices, such as SRAM and DRAM. However, the existing technology lacks application in small devices such as MEMS sensors. Summary of the invention

[0004] One advantage of the present application is that it provides a piezoresistive sensor, a method for manufacturing a piezoresistive sensor structure, and a piezoresistive sensor that can apply PUF key technology. By adjusting the voltage difference between two pressure simulation electrodes, the magnitude of the external pressure on the piezoresistive sensor structure can be simulated, and by adjusting the driving voltage of the piezoresistive sensor structure, it can be used to generate the excitation-response pairs required for PUF technology, so that PUF key technology can be implemented on the piezoresistive sensor.

[0005] Based on this, in order to achieve at least one of the above advantages or other advantages and purposes of the present application, the present application provides a piezoresistive sensor structure, including: A first substrate, and a second substrate disposed below the first substrate, wherein a cavity is disposed on an upper surface of the second substrate, and a sensitive film is formed in a region of the first substrate above the cavity; A Wheatstone bridge structure disposed on the first substrate; A first pressure simulation electrode is arranged on the surface of the sensitive film facing the cavity; A second pressure simulation electrode is arranged on the surface of the second substrate at the bottom of the cavity.

[0006] With such a configuration, different voltages can be applied to the surface of the cavity with the aid of the first pressure simulation electrode and the second pressure simulation electrode to simulate the application of different pressures to the piezoresistive sensor structure, thereby obtaining corresponding responses unique to the piezoresistive sensor structure and output based on different excitations.

[0007] According to an embodiment of the present application, a projection of the first pressure simulation electrode on the surface of the first substrate coincides with a projection of the second pressure simulation electrode on the surface of the first substrate.

[0008] Such a configuration allows the voltage distribution in the cavity to be relatively uniform when voltage is applied to both sides of the cavity, thereby preventing uneven voltage distribution from affecting the normal use of the piezoresistive sensor structure. In addition, the relatively uniform voltage distribution in the cavity can also reduce the occurrence of material aging or damage caused by excessive voltage at local locations. Compared with the solution in which the projection of the first pressure simulation electrode on the surface of the first substrate does not overlap with the projection of the second pressure simulation electrode on the surface of the first substrate, the piezoresistive sensor structure provided by this solution has higher stability and longer service life.

[0009] According to one embodiment of the present application, the piezoresistive sensor structure further includes: A first through hole is provided in the surface of the first substrate, wherein the first through hole is filled with a conductive material; A first electrode lead is disposed on the upper surface of the first substrate, and the first electrode lead is electrically connected to the conductive material in the first through hole to lead out the first pressure simulation electrode.

[0010] According to one embodiment of the present application, the piezoresistive sensor structure further includes: A second through hole is provided in the surface of the second substrate, wherein the second through hole is filled with a conductive material; A second electrode lead is disposed on the lower surface of the second substrate, and the second electrode lead is electrically connected to the conductive material in the second through hole to lead out the second pressure simulation electrode.

[0011] With such arrangement, the first pressure simulation electrode can be led out with the help of the first through hole and the first electrode lead, and the second pressure simulation electrode can be led out with the help of the second through hole and the second electrode lead, so that a voltage can be applied between the first electrode lead and the second electrode lead, so as to apply a voltage on both sides of the cavity with the help of the first pressure simulation electrode and the second pressure simulation electrode, thereby simulating the pressure applied on both sides of the cavity, thereby obtaining the response output by the piezoresistive sensor structure based on different excitations.

[0012] According to one embodiment of the present application, the piezoresistive sensor structure further includes: a first insulating layer disposed between the first substrate and the first pressure simulation electrode; a second insulating layer disposed between the second substrate and the second pressure simulation electrode; A third insulating layer disposed between the sidewall of the first through hole and the conductive material; A fourth insulating layer is disposed between the sidewall of the second through hole and the conductive material.

[0013] In this way, by setting the first insulating layer between the first substrate and the first pressure simulation electrode, setting the second insulating layer between the second substrate and the second pressure simulation electrode, setting the third insulating layer between the first through-hole sidewall and the conductive material, and setting the fourth insulating layer between the second through-hole sidewall and the conductive material, the current in the piezoresistive sensor structure can be effectively controlled to flow according to the designed loop, so as to prevent the current in the piezoresistive sensor structure from not flowing according to the designed loop, thereby causing a short circuit or open circuit in part of the circuit in the piezoresistive sensor structure, thereby affecting the normal operation of the piezoresistive sensor structure; it can also prevent the load through which the current flows from becoming larger due to the current in the piezoresistive sensor structure not flowing according to the designed loop, thereby increasing the energy loss of the piezoresistive sensor structure; in addition, this scheme can also prevent the occurrence of electric shock accidents caused by the staff when making or using the piezoresistive sensor structure because the first insulating layer, the second insulating layer, the third insulating layer and the fourth insulating layer are not set. Compared with the scheme without setting each insulating layer, the piezoresistive sensor structure provided by this scheme has higher stability, higher overall energy utilization rate, and relatively better safety performance.

[0014] According to an embodiment of the present application, the Wheatstone bridge structure includes: four first varistors disposed in the upper surface of the sensitive film region of the first substrate, and a third electrode lead disposed on the upper surface of the first substrate, the third electrode lead electrically connecting the four first varistors; Alternatively, the Wheatstone bridge structure comprises: two second varistors arranged in the upper surface of the sensitive film region of the first substrate, and two third varistors arranged in the lower surface of the sensitive film region of the first substrate; Two third through holes are provided in the sensitive film area of ​​the first substrate, and the third through holes are filled with conductive material; A fourth electrode lead is disposed on the upper surface of the first substrate, and a fifth electrode lead is disposed on the lower surface of the first substrate, wherein the fourth electrode lead and the fifth electrode lead are electrically connected to the conductive material in the third through hole, and are electrically connected to the two second varistors and the two third varistors to form a Wheatstone bridge; The first pressure simulation electrode is electrically insulated from the two third piezoresistors and the fifth electrode lead; Alternatively, the Wheatstone bridge structure includes a first Wheatstone bridge disposed on the upper surface of the sensitive thin film region of the first substrate and a second Wheatstone bridge disposed on the lower surface of the sensitive thin film region of the first substrate.

[0015] With such an arrangement, a Wheatstone bridge can be selectively arranged on the upper surface of the sensitive film area of ​​the first substrate according to the actual application environment; or a partial structure of a Wheatstone bridge can be arranged on the upper surface of the sensitive film area of ​​the first substrate, and the other partial structure of a Wheatstone bridge can be arranged on the lower surface of the sensitive film area of ​​the first substrate; or two Wheatstone bridges can be arranged on the upper surface and the lower surface of the sensitive film area respectively. Compared with the solution of only fixedly arranging one Wheatstone bridge, the piezoresistive sensor structure provided by this solution is more flexible, and different Wheatstone bridge structures can be selected based on different usage environments.

[0016] According to another aspect of the present application, the present application provides a method for manufacturing a piezoresistive sensor structure, comprising: Providing a first substrate, and forming a first blind hole on the first substrate; Forming a patterned first conductive material layer on the first substrate to form a first pressure simulation electrode on the first substrate, wherein the first conductive material layer fills the first blind hole; Providing a second substrate, forming a groove on the second substrate, and forming a second blind hole at the bottom of the groove; Forming a patterned second conductive material layer at the bottom of the groove to form a second pressure simulation electrode at the bottom of the groove, wherein the second conductive material layer fills the second blind hole; Bonding the second substrate to the inverted first substrate to form a cavity; Thinning the lower surface of the second substrate until the second conductive material in the second blind hole is exposed, forming a second electrode lead on the lower surface of the second substrate, wherein the second electrode lead is electrically connected to the second conductive material in the second blind hole; Thinning the inverted surface of the first substrate until the first conductive material in the first blind hole is exposed to form a sensitive film; forming a plurality of varistors in the inverted surface of the first substrate; A first electrode lead is formed on the surface of the first substrate having the varistor, the first electrode lead is electrically connected to the plurality of varistors to form a Wheatstone bridge structure, and the first electrode lead is electrically connected to the first conductive material in the first blind hole.

[0017] According to other aspects of the present application, the present application provides a piezoresistive sensor, comprising: a power module, a processor, a communication module, a storage module, an interface module, and the above-mentioned piezoresistive sensor structure; the power module is used to provide a driving voltage and a pressure simulation voltage for the processor, the communication module, the storage module, the interface module, and the piezoresistive sensor structure; the processor is electrically connected to the Wheatstone bridge structure, and is used to calculate the resistance value of the piezoresistive sensor structure, and is used to control the working state of the power module; Among them, when the piezoresistive sensor is in a testing state, the power supply module is electrically connected to the driving voltage input terminal, the first pressure simulation electrode and the second pressure simulation electrode of the piezoresistive sensor structure; when the piezoresistive sensor is in a working state, the power supply module is disconnected from the first pressure simulation electrode and the second pressure simulation electrode of the piezoresistive sensor structure.

[0018] With such an arrangement, the power module can be used to provide electrical energy, driving voltage and pressure simulation voltage to other modules in the piezoresistive sensor to test the resistance of the piezoresistive sensor structure under different driving voltages and different pressure simulation voltages.

[0019] According to one embodiment of the present application, the processor is further used to control the voltage value of the driving voltage output by the power module to the piezoresistive sensor structure in response to a test signal from an external test device.

[0020] In this way, the processor can receive a test signal sent by an external test device or test terminal, and in response to the test signal, control the voltage value of the driving voltage output by the power supply module to the piezoresistive sensor structure, so as to subsequently apply different driving voltages and different pressure simulation voltages to the piezoresistive sensor structure, thereby obtaining that the piezoresistive sensor structure outputs different responses under different driving voltages and different pressure simulation voltages.

[0021] According to one embodiment of the present application, in a test state, the processor is further used to control the voltage output by the power module to the first pressure simulation electrode and / or the second pressure simulation electrode in response to a test signal from an external test device.

[0022] According to one embodiment of the present application, the piezoresistive sensor is a MEMS sensor or an NMES sensor; the piezoresistive sensor is a piezoresistive pressure sensor, a piezoresistive force sensor, a piezoresistive displacement sensor, a piezoresistive mass sensor, a piezoresistive strain sensor, a piezoresistive flow sensor, a piezoresistive torque sensor, a piezoresistive vibration sensor, a piezoresistive liquid level sensor, a piezoresistive gyroscope, a piezoresistive gas sensor, a piezoresistive magnetic sensor, a piezoresistive biosensor, a piezoresistive humidity sensor, a piezoresistive temperature sensor, a piezoresistive chemical sensor, a piezoresistive acceleration sensor, and a piezoresistive inertial sensor.

[0023] Beneficial effect: The piezoresistive sensor disclosed in the embodiment of the present application has an attractive force between two energized plates due to the electrostatic effect. The voltage difference between the first pressure simulation electrode and the second pressure simulation electrode can be adjusted to simulate the application of different pressures to the piezoresistive sensor structure. The driving voltage of the piezoresistive sensor structure can be adjusted to generate the excitation-response pairs required for the PUF technology, and the PUF key technology can be implemented on the piezoresistive sensor. Compared with the solution of directly applying pressure to the piezoresistive sensor structure, this solution applies different voltages on the surface of the cavity through the first pressure simulation electrode and the second pressure simulation electrode to simulate the application of different pressures to the piezoresistive sensor structure. Compared with the solution of applying pressure, the solution of applying voltage is easier to quantify and easier to reproduce. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 A schematic structural diagram of a piezoresistive sensor structure provided for one embodiment of the present application; Figure 2 A schematic flow chart of a method for manufacturing a piezoresistive sensor structure provided in other embodiments of the present application; Figure 3 A schematic diagram of the structure of a power supply module in the piezoresistive sensor provided in the above embodiment is shown; Figure 4 A schematic structural diagram of a piezoresistive sensor structure provided in another embodiment of the present application.

[0026] Figure numerals: 1. piezoresistive sensor structure; 10. first substrate; 11. first pressure simulation electrode; 12. sensitive film; 13. Wheatstone bridge structure; 14. third electrode lead; 15. first piezoresistance; 101. first through hole; 102. first insulating layer; 103. third insulating layer; 20. second substrate; 21. second pressure simulation electrode; 201. second through hole; 202. second insulating layer; 203. fourth insulating layer; U1. driving voltage; U2. output voltage; S1. first switch module. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0028] As described in the background technology, the prior art lacks PUF applications for small devices such as MEMS sensors. The inventors have studied that the reason is that small devices such as MEMS sensors lack PUF characteristic values ​​that can be used to generate PUF keys in PUF key applications, that is, corresponding stimulus-response pairs (CRPs). Based on this, the inventors found that for MEMS piezoresistive sensors, when the driving voltage changes, the resistance-pressure coefficient of the MEMS piezoresistive sensor will also change accordingly, and for the same piezoresistive sensor, this change characteristic is unique. Therefore, the driving voltage can be used as the excitation and the resistance-pressure coefficient can be used as the response, that is, the resistance-pressure coefficient under different driving voltages can be used as the PUF characteristic value of the MEMS piezoresistive sensor.

[0029] Based on this, the embodiment of the present application proposes a piezoresistive sensor, including: a power module, a processor, a communication module, a storage module, an interface module, and a piezoresistive sensor structure 1 (the piezoresistive sensor structure 1 is as shown in FIG. Figure 1 The power module is used to provide power to the processor, the communication module, the storage module, the interface module, and the piezoresistive sensor structure 1, and the voltage input to the piezoresistive sensor structure 1 is the driving voltage U1; the processor is electrically connected to the Wheatstone bridge structure 13, and is used to calculate the resistance value of the piezoresistive sensor structure 1, and is used to control the working state of the power module; the piezoresistive sensor structure has a first pressure simulation electrode 11 and a second pressure simulation electrode 21, and the power module provides a pressure simulation voltage for the first pressure simulation electrode 11 and the second pressure simulation electrode 21.

[0030] Wherein, when the piezoresistive sensor is in the test state, the power module is electrically connected to the driving voltage U1 input terminal, the first pressure simulation electrode 11 and the second pressure simulation electrode 21 of the piezoresistive sensor structure 1; when the piezoresistive sensor is in the working state, the power module is disconnected from the first pressure simulation electrode 11 and the second pressure simulation electrode 21 of the piezoresistive sensor structure 1. The power module can be used to provide electrical energy, driving voltage U1 and pressure simulation voltage to other modules in the piezoresistive sensor to test the resistance of the piezoresistive sensor structure 1 under different driving voltages U1 and different pressure simulation voltages.

[0031] In particular, the voltage output by the power module is the output voltage U2, ie, the output voltage U2 of the power supply.

[0032] In particular, a driving voltage adjustment unit is provided in the power module to adjust the driving voltage input to the piezoresistive sensor structure 1. The driving voltage adjustment unit can be a voltage adjustment circuit composed of one or more of a switching regulator, a resistor divider, a Zener diode, and a sliding resistor. This embodiment takes a resistor divider circuit as an example.

[0033] like Figure 3 As shown, the resistor voltage divider circuit includes a resistor component and a first switch module S1. The resistor component includes multiple resistors R1-Rk. The multiple resistors are connected in series in sequence, and the resistor component is connected to a power supply. The voltages across several resistors can be connected according to different requirements.

[0034] It is worth noting that the processor is also used to control the change of the voltage value of the driving voltage U1 output by the power module to the piezoresistive sensor structure 1 in response to the test signal of the external test equipment.

[0035] In order to test the resistance-pressure coefficient under different driving voltages, different pressure values ​​need to be applied to the piezoresistive sensor structure 1, which is achieved in this embodiment by applying different pressure simulation voltages to the first pressure simulation electrode 11 and the second pressure simulation electrode 21. The voltages between the first pressure simulation electrode 11 and the second pressure simulation electrode 21 are different, and the suction forces generated between the two are different, which can be used to simulate different pressures, thereby obtaining multiple resistance-pressure coefficients, and combined with the adjustment of the driving voltage, multiple CRP response pairs with the driving voltage as the excitation and the resistance-pressure coefficient as the response can be obtained. These CRP response pairs can be further used to generate PUF keys, so that the security of the piezoresistive sensor can be verified by applying the PUF key technology.

[0036] It should be noted that the processor can receive a test signal sent from an external test device or test terminal, and in response to the test signal, control the voltage value of the driving voltage U1 output by the power module to the piezoresistive sensor structure 1, and control the pressure simulation voltage output to the first pressure simulation electrode 11 and the second pressure simulation electrode 21, thereby obtaining a response of the piezoresistive sensor structure 1 based on different driving voltages U1 and different pressure simulation voltage outputs.

[0037] It is worth noting that the piezoresistive sensor is a MEMS sensor or an NMES sensor; the piezoresistive sensor includes but is not limited to a piezoresistive pressure sensor, a piezoresistive force sensor, a piezoresistive displacement sensor, a piezoresistive mass sensor, a piezoresistive strain sensor, a piezoresistive flow sensor, a piezoresistive torque sensor, a piezoresistive vibration sensor, a piezoresistive liquid level sensor, a piezoresistive gyroscope, a piezoresistive gas sensor, a piezoresistive magnetic sensor, a piezoresistive biosensor, a piezoresistive humidity sensor, a piezoresistive temperature sensor, a piezoresistive chemical sensor, a piezoresistive acceleration sensor, and a piezoresistive inertial sensor.

[0038] When the piezoresistive sensor is a wireless sensor, the piezoresistive sensor further includes an antenna module and a communication module, and the antenna module and the communication module are used to establish wireless communication with an external test terminal or test equipment.

[0039] The piezoresistive sensor provided in this embodiment can be applied to PUF key technology to verify the security of the piezoresistive sensor. In order to further illustrate the structure of the piezoresistive sensor, another embodiment of the present application discloses a specific design of a specific piezoresistive sensor structure 1. The piezoresistive sensor structure 1 proposed in another embodiment of the present application is described below in conjunction with the accompanying drawings.

[0040] The design idea of ​​the piezoresistive sensor structure 1 disclosed in the embodiment of the present application is to add a pressure simulation electrode to the traditional piezoresistive sensor structure 1 to simulate the size of the external pressure on the piezoresistive sensor structure 1, and to adjust the driving voltage U1 of the piezoresistive sensor structure 1 to obtain the excitation-response pair required by the PUF technology. The piezoresistive sensor structure 1 includes but is not limited to a MEMS piezoresistive sensor structure 1 or a NEMS piezoresistive sensor structure 1. This embodiment only takes the structure of a MEMS piezoresistive sensor as an example for explanation.

[0041] Specifically, Figure 1 As shown, the piezoresistive sensor structure 1 includes: A first substrate 10, and a second substrate 20 disposed below the first substrate 10, wherein a cavity 30 is disposed on an upper surface of the second substrate 20, and a sensitive film 12 is formed in a region of the first substrate 10 above the cavity 30; A Wheatstone bridge structure 13 disposed on the first substrate 10; A first pressure simulation electrode 11 is arranged on the surface of the sensitive film 12 facing the cavity; A second pressure simulation electrode 21 is disposed on the surface of the second substrate 20 at the bottom of the cavity.

[0042] The first substrate 10 may be made of single crystal silicon with a thickness of 10 μm-50 μm. The second substrate 20 may be made of single crystal silicon or glass, preferably a BF33 glass sheet with a thickness of 200 μm-1000 μm. The cavity depth on the upper surface of the second substrate 20 is 1 μm-50 μm.

[0043] In particular, the shape of the sensitive film 12, ie, the diaphragm of the piezoresistive sensor, includes but is not limited to a circular, rectangular, annular, or porous structure.

[0044] The embodiment of the present application applies different pressure simulation potentials to the first pressure simulation electrode 11 and the second pressure simulation electrode 21 to form an attractive force between the two pressure simulation electrodes. Under the action of the attractive force, the sensitive film 12 is deformed to simulate the application of different pressures to the piezoresistive sensor structure 1. Compared with the solution of directly applying pressure to the piezoresistive sensor structure 1, the solution of applying voltage in the present embodiment is easier to quantify and easier to reproduce.

[0045] It is understandable that, according to Coulomb's law, like charges repel each other, and unlike charges attract each other. When two objects with the same charge approach each other, a repulsive force is generated between them; and when objects with opposite charges approach each other, an attractive force is generated. The magnitude of this force is proportional to the amount of charge and inversely proportional to the square of the distance. In other words, the greater the voltage between the first pressure simulation electrode 11 and the second pressure simulation electrode 21, the greater the attraction between the two, and then the attraction is converted into mechanical deformation with the help of the sensitive film 12, and then the resistance value of the piezoresistive sensor structure 1 is changed through the piezoresistive effect.

[0046] In other embodiments of the present application, the projection of the first pressure simulation electrode 11 on the surface of the first substrate 10 coincides with the projection of the second pressure simulation electrode 21 on the surface of the first substrate 10, so that when power is on, the attraction between the two pressure simulation electrodes is more uniform, and the relatively uniform voltage distribution can also reduce the occurrence of material aging or damage caused by excessive voltage in local locations. Compared with the solution in which the projection of the first pressure simulation electrode 11 on the surface of the first substrate 10 does not coincide with the projection of the second pressure simulation electrode 21 on the surface of the first substrate 10, the piezoresistive sensor structure 1 provided by this solution has higher stability and longer service life.

[0047] In order to better realize the functions of piezoresistive sensors, such as Figure 1 As shown, the piezoresistive sensor structure 1 also includes: A first through hole 101 is provided in the surface of the first substrate 10, wherein the first through hole 101 is filled with a conductive material; A first electrode lead is disposed on the upper surface of the first substrate 10 , and the first electrode lead is electrically connected to the conductive material in the first through hole 101 to lead out the first pressure simulation electrode 11 .

[0048] Furthermore, the piezoresistive sensor structure 1 further includes: A second through hole 201 is provided in the surface of the second substrate 20, and the second through hole 201 is filled with a conductive material; A second electrode lead is disposed on the lower surface of the second substrate 20 , and the second electrode lead is electrically connected to the conductive material in the second through hole 201 to lead out the second pressure simulation electrode 21 .

[0049] In particular, the conductive material filled in the first through hole 101 and the second through hole 201 includes but is not limited to metal materials and the like, preferably copper.

[0050] It should be noted that the first pressure simulation electrode 11 can be led out with the help of the first through hole 101 and the first electrode lead, and the second pressure simulation electrode 21 can be led out with the help of the second through hole 201 and the second electrode lead, so that by energizing the first electrode lead and the second electrode lead, voltage can be applied to the first pressure simulation electrode 11 and the second pressure simulation electrode 21.

[0051] In other embodiments of the present application, the piezoresistive sensor structure 1 further includes: A first insulating layer 102 disposed between the first substrate 10 and the first pressure simulation electrode 11; A second insulating layer 202 disposed between the second substrate 20 and the second pressure simulation electrode 21; A third insulating layer 103 disposed between the side wall of the first through hole 101 and the conductive material; A fourth insulating layer 203 is disposed between the sidewall of the second through hole 201 and the conductive material.

[0052] In particular, the materials of the first insulating layer 102 , the second insulating layer 202 , the third insulating layer 103 and the fourth insulating layer 203 include but are not limited to silicon nitride, aluminum oxide, aluminum nitride and silicon dioxide.

[0053] It should be noted that by setting the first insulating layer 102 between the first substrate 10 and the first pressure simulation electrode 11, setting the second insulating layer 202 between the second substrate 20 and the second pressure simulation electrode 21, setting the third insulating layer 103 between the side wall of the first through hole 101 and the conductive material, and setting the fourth insulating layer 203 between the side wall of the second through hole 201 and the conductive material, the current in the piezoresistive sensor structure 1 can be effectively controlled to flow in a designed loop to prevent the current in the piezoresistive sensor structure 1 from not flowing in a designed loop, thereby causing the The present invention can prevent the occurrence of a situation where part of the circuit in the piezoresistive sensor structure 1 is short-circuited or open-circuited, thereby affecting the normal operation of the piezoresistive sensor structure 1; it can also prevent the current in the piezoresistive sensor structure 1 from not flowing according to the designed loop, resulting in the load through which the current flows becoming larger, thereby increasing the energy loss of the piezoresistive sensor structure 1; in addition, the present invention can also prevent the occurrence of electric shock accidents caused by the lack of the first insulating layer 102, the second insulating layer 202, the third insulating layer 103 and the fourth insulating layer 203 when the staff is making or using the piezoresistive sensor structure 1. Compared with the solution without setting each insulating layer, the piezoresistive sensor structure 1 provided by the present invention has higher stability, higher overall energy utilization rate, and relatively better safety performance.

[0054] Piezoresistive sensors test external pressure and other parameters based on the piezoresistive effect of resistors in a Wheatstone bridge. The so-called piezoresistive effect refers to the phenomenon that in some materials, when mechanical stress is applied, the resistivity changes. This effect is caused by stress causing changes in the crystal structure inside the material, which affects the mobility and concentration of carriers. The piezoresistive effect is particularly significant in semiconductor materials. When external force acts on a semiconductor, it causes the lattice to deform, thereby changing the scattering process of carriers and causing the resistivity of the material to change.

[0055] In the embodiment of the present application, the Wheatstone bridge structure 13 is composed of four resistors located on the surface of the sensitive film, such as Figure 1 As shown, the specific structure may include: four first varistors 15 arranged in the upper surface of the sensitive film 12 region of the first substrate 10, and a third electrode lead 14 arranged on the upper surface of the first substrate 10, wherein the third electrode lead 14 is electrically connected to the four first varistors 15; In another embodiment of the present application, the Wheatstone bridge structure is composed of two resistors located on the upper surface of the sensitive film and two resistors located on the lower surface of the sensitive film. The specific structure may include: two second varistors arranged in the upper surface of the sensitive film region of the first substrate, and two third varistors arranged in the lower surface of the sensitive film region of the first substrate; Two third through holes are provided in the sensitive film area of ​​the first substrate, and the third through holes are filled with conductive material; A fourth electrode lead is disposed on the upper surface of the first substrate, and a fifth electrode lead is disposed on the lower surface of the first substrate, wherein the fourth electrode lead and the fifth electrode lead are electrically connected to the conductive material in the third through hole, and are electrically connected to the two second varistors and the two third varistors to form a Wheatstone bridge; The first pressure simulation electrode is electrically insulated from the two third piezoresistors and the fifth electrode lead; To further improve the sensitivity of the Wheatstone bridge, Figure 4 As shown, in another embodiment of the present application, the Wheatstone bridge structure 13 is composed of a Wheatstone bridge located on the upper surface of the sensitive film and a Wheatstone bridge located on the lower surface of the sensitive film, including a first Wheatstone bridge arranged on the upper surface of the sensitive film 12 area of ​​the first substrate 10 and a second Wheatstone bridge arranged on the lower surface of the sensitive film 12 area of ​​the first substrate 10.

[0056] It should be noted that, according to the actual application environment, a Wheatstone bridge can be selectively set on the upper surface of the sensitive film 12 area of ​​the first substrate 10; or a partial structure of a Wheatstone bridge can be set on the upper surface of the sensitive film 12 area of ​​the first substrate 10, and the other partial structure of a Wheatstone bridge can be set on the lower surface of the sensitive film 12 area of ​​the first substrate 10; or two Wheatstone bridges can be respectively set on the upper surface and the lower surface of the sensitive film 12 area. Compared with the solution of only fixedly setting one Wheatstone bridge, the piezoresistive sensor structure 1 provided by this solution is more flexible, and different Wheatstone bridge structures 13 can be selected based on different usage environments.

[0057] In another embodiment of the present application, a method for manufacturing a piezoresistive sensor structure is provided. Figure 1 The piezoresistive sensor structure is shown in FIG. Figure 2 As shown, the method comprises the following steps: S11, providing a first substrate 10, and forming a first blind hole on the first substrate 10; S12, forming a patterned first conductive material layer on the first substrate 10 to form a first pressure simulation electrode 11 on the first substrate 10, wherein the first conductive material layer fills the first blind hole; S13, providing a second substrate 20, forming a groove on the second substrate 20, and forming a second blind hole at the bottom of the groove; S14, forming a patterned second conductive material layer at the bottom of the groove to form a second pressure simulation electrode 21 at the bottom of the groove, and the second conductive material layer fills the second blind hole; S15, bonding the second substrate 20 to the inverted first substrate 10 to form a cavity; S16, thinning the lower surface of the second substrate 20 until the second conductive material in the second blind hole is exposed, forming a second electrode lead on the lower surface of the second substrate 20, wherein the second electrode lead is electrically connected to the second conductive material in the second blind hole; S17, thinning the surface of the inverted first substrate 10 until the first conductive material in the first blind hole is exposed to form a sensitive film 12; S18, forming a plurality of varistors on the surface of the inverted first substrate 10; S19, forming a first electrode lead on the surface of the first substrate 10 having a varistor, wherein the first electrode lead is electrically connected to the plurality of varistors to form a Wheatstone bridge structure 13, and the first electrode lead is electrically connected to the first conductive material in the first blind hole.

[0058] If you need to make Figure 4 The piezoresistive sensor structure shown can be adaptively increased by adding relevant steps.

[0059] In particular, other embodiments of the present application further provide a method for generating a PUF characteristic value based on the piezoresistive sensor, which can apply PUF technology to the piezoresistive sensor disclosed in the above embodiments. The method for generating a PUF characteristic value includes the following steps: Step A: providing a piezoresistive sensor, turning on the power supply of the piezoresistive sensor, wherein the piezoresistive sensor comprises a power supply, a driving voltage U1 adjustment circuit and a piezoresistive sensor structure 1; the driving voltage U1 adjustment circuit is used to adjust the driving voltage U1 input to the piezoresistive sensor; the piezoresistive sensor structure 1 comprises a pressure simulation structure and a Wheatstone bridge, and the pressure simulation structure is used to simulate the change of the external pressure to which the piezoresistive sensor is subjected; Step B: inputting a driving voltage U1 to the piezoresistive sensor via the driving voltage U1 adjustment circuit; Step C1: Under the driving voltage U1, the pressure simulation structure simulates M1 group of external pressure groups, obtains the resistance-pressure coefficient K of the piezoresistive sensor under each group of external pressure, and obtains the M1 group of resistance-pressure coefficient K, each group of external pressure groups includes 2 different pressure values, and the resistance under each group of external pressure is 2; Step C2: measuring an initial output voltage V0 of the piezoresistive sensor under a driving voltage U1, wherein the initial output voltage V0 is an output voltage when an additional external pressure applied to the piezoresistive sensor is zero; Step D: adjusting the driving voltage U1, repeating steps B-C1, until a plurality of resistance-pressure coefficients K under N sets of driving voltage U1 are obtained, the number of K being M1+M2+......+Mn, where N and M1-Mn are both positive integers; Step E: using the N groups of driving voltages U1 as excitations and multiple K values ​​under each driving voltage U1 as responses to generate PUF characteristic values.

[0060] The above-mentioned PUF characteristic value generation method based on the piezoresistive sensor utilizes the fact that the resistance-pressure coefficient K of the piezoresistive sensor under different driving voltages U1 is also different, but K has a unique and stable characteristic under different driving voltages U1. The driving voltage U1 in the piezoresistive sensor is used as excitation, and the resistance-pressure coefficient under different pressures is used as response to generate the PUF characteristic value of the sensor. There is no need to increase additional design and production costs, thereby reducing the PUF cost.

[0061] In particular, the values ​​of M1, M2, ... Mn may be the same or different.

[0062] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but are not limited to this.

[0063] Unless otherwise defined, all technical and scientific terms used in the specification of this application have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in the specification of this application includes any and all combinations of one or more related listed items.

[0064] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0065] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A piezoresistive sensor structure, characterized in that: include: A first substrate, and a second substrate disposed below the first substrate, wherein a cavity is disposed on an upper surface of the second substrate, and a sensitive film is formed in a region of the first substrate above the cavity; A Wheatstone bridge structure disposed on the first substrate; A first pressure simulation electrode is arranged on the surface of the sensitive film facing the cavity; A second pressure simulation electrode is arranged on the surface of the second substrate at the bottom of the cavity.

2. The piezoresistive sensor structure according to claim 1, characterized in that: The projection of the first pressure simulation electrode on the surface of the first substrate coincides with the projection of the second pressure simulation electrode on the surface of the first substrate.

3. The piezoresistive sensor structure according to claim 2, characterized in that: Also includes: A first through hole is provided in the surface of the first substrate, wherein the first through hole is filled with a conductive material; A first electrode lead is disposed on the upper surface of the first substrate, and the first electrode lead is electrically connected to the conductive material in the first through hole to lead out the first pressure simulation electrode.

4. The piezoresistive sensor structure according to claim 3, characterized in that: Also includes: A second through hole is provided in the surface of the second substrate, wherein the second through hole is filled with a conductive material; A second electrode lead is disposed on the lower surface of the second substrate, and the second electrode lead is electrically connected to the conductive material in the second through hole to lead out the second pressure simulation electrode.

5. The piezoresistive sensor structure according to claim 4, characterized in that: Also includes: a first insulating layer disposed between the first substrate and the first pressure simulation electrode; a second insulating layer disposed between the second substrate and the second pressure simulation electrode; A third insulating layer disposed between the sidewall of the first through hole and the conductive material; A fourth insulating layer is disposed between the sidewall of the second through hole and the conductive material.

6. The piezoresistive sensor structure according to claim 1, characterized in that: The Wheatstone bridge structure comprises: four first varistors arranged in the upper surface of the sensitive film region of the first substrate, and a third electrode lead arranged on the upper surface of the first substrate, wherein the third electrode lead is electrically connected to the four first varistors; Alternatively, the Wheatstone bridge structure comprises: two second varistors arranged in the upper surface of the sensitive film region of the first substrate, and two third varistors arranged in the lower surface of the sensitive film region of the first substrate; Two third through holes are provided in the sensitive film area of ​​the first substrate, and the third through holes are filled with conductive material; A fourth electrode lead is disposed on the upper surface of the first substrate, and a fifth electrode lead is disposed on the lower surface of the first substrate, wherein the fourth electrode lead and the fifth electrode lead are electrically connected to the conductive material in the third through hole, and are electrically connected to the two second varistors and the two third varistors to form a Wheatstone bridge; The first pressure simulation electrode is electrically insulated from the two third piezoresistors and the fifth electrode lead; Alternatively, the Wheatstone bridge structure includes a first Wheatstone bridge disposed on the upper surface of the sensitive thin film region of the first substrate and a second Wheatstone bridge disposed on the lower surface of the sensitive thin film region of the first substrate.

7. A method for manufacturing a piezoresistive sensor structure, characterized in that: include: Providing a first substrate, and forming a first blind hole on the first substrate; Forming a patterned first conductive material layer on the first substrate to form a first pressure simulation electrode on the first substrate, wherein the first conductive material layer fills the first blind hole; Providing a second substrate, forming a groove on the second substrate, and forming a second blind hole at the bottom of the groove; Forming a patterned second conductive material layer at the bottom of the groove to form a second pressure simulation electrode at the bottom of the groove, wherein the second conductive material layer fills the second blind hole; Bonding the second substrate to the inverted first substrate to form a cavity; Thinning the lower surface of the second substrate until the second conductive material in the second blind hole is exposed, forming a second electrode lead on the lower surface of the second substrate, wherein the second electrode lead is electrically connected to the second conductive material in the second blind hole; Thinning the inverted surface of the first substrate until the first conductive material in the first blind hole is exposed to form a sensitive film; forming a plurality of varistors in the inverted surface of the first substrate; A first electrode lead is formed on the surface of the first substrate having the varistor, the first electrode lead is electrically connected to the plurality of varistors to form a Wheatstone bridge structure, and the first electrode lead is electrically connected to the first conductive material in the first blind hole.

8. A piezoresistive sensor, characterized in that: include: A power module, a processor, a communication module, a storage module, an interface module, and a piezoresistive sensor structure according to any one of claims 1 to 6; the power module is used to provide a driving voltage and a pressure simulation voltage for the processor, the communication module, the storage module, the interface module, and the piezoresistive sensor structure; the processor is electrically connected to the Wheatstone bridge structure, and is used to calculate the resistance value of the piezoresistive sensor structure and to control the working state of the power module; Among them, when the piezoresistive sensor is in a testing state, the power supply module is electrically connected to the driving voltage input terminal, the first pressure simulation electrode and the second pressure simulation electrode of the piezoresistive sensor structure; when the piezoresistive sensor is in a working state, the power supply module is disconnected from the first pressure simulation electrode and the second pressure simulation electrode of the piezoresistive sensor structure.

9. The piezoresistive sensor according to claim 8, characterized in that: The processor is also used to control the change of the voltage value of the driving voltage output by the power module to the piezoresistive sensor structure in response to a test signal from an external test device.

10. The piezoresistive sensor according to claim 9, characterized in that: In the test state, the processor is further used to control the voltage output by the power module to the first pressure simulation electrode and / or the second pressure simulation electrode in response to a test signal from an external test device.

11. The piezoresistive sensor according to any one of claims 8 to 10, characterized in that: The piezoresistive sensor is a MEMS sensor or an NMES sensor; the piezoresistive sensor is a piezoresistive pressure sensor, a piezoresistive force sensor, a piezoresistive displacement sensor, a piezoresistive mass sensor, a piezoresistive strain sensor, a piezoresistive flow sensor, a piezoresistive torque sensor, a piezoresistive vibration sensor, a piezoresistive liquid level sensor, a piezoresistive gyroscope, a piezoresistive gas sensor, a piezoresistive magnetic sensor, a piezoresistive biosensor, a piezoresistive humidity sensor, a piezoresistive temperature sensor, a piezoresistive chemical sensor, a piezoresistive acceleration sensor, and a piezoresistive inertial sensor.

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