CN118603374A - Piezoresistive pressure sensor and electronic equipment - Google Patents

Abstract

The present invention discloses a piezoresistive pressure sensor and electronic device, which relates to the technical field of pressure sensors, wherein the pressure sensor includes a supporting layer, an N-type sensitive layer and a bridge assembly, the supporting layer includes a first surface and a cavity; the N-type sensitive layer is arranged on the first surface and covers the cavity; the bridge assembly is arranged on the N-type sensitive layer and includes a plurality of P-type piezoresistors, and the plurality of P-type piezoresistors are sequentially connected in series to form a ring structure; the P-type piezoresistors include a first piezoresistor and a second piezoresistor connected in series, the orthographic projection of the first piezoresistor to the supporting layer at least partially overlaps with the cavity, and the orthographic projection of the second piezoresistor to the supporting layer is misaligned with the cavity, and when the pressure sensor is subjected to non-test pressure, the resistance of one of the first piezoresistor and the second piezoresistor increases, and the resistance of the other decreases. The piezoresistive pressure sensor and electronic device provided by the technical solution of the present invention are intended to improve the measurement accuracy of the piezoresistive pressure sensor when subjected to external pressure.

Description

Piezoresistive pressure sensor and electronic equipment

Technical Field

The present invention relates to the technical field of pressure sensors, and in particular to a piezoresistive pressure sensor and electronic equipment.

Background Art

Piezoresistive pressure sensors have the characteristics of small size, light weight, easy integration, ultra-high sensitivity and resolution, and are widely used in various fields such as aerospace, aviation, biomedicine, meteorology, geology, and seismic measurement.

The piezoresistive pressure sensor of the related technology is prone to deviations in sensor test accuracy when subjected to pressure from external factors (such as pressure applied to the sensor surface during packaging, or uneven thermal stress generated during use due to differences in thermal expansion coefficients between components).

Therefore, it is urgent to design a new piezoresistive pressure sensor and electronic equipment to solve the above problems.

Summary of the invention

The main purpose of the present invention is to provide a piezoresistive pressure sensor and an electronic device, aiming to improve the measurement accuracy of the piezoresistive pressure sensor when subjected to external pressure.

To achieve the above-mentioned purpose, an embodiment of the present invention provides a piezoresistive pressure sensor, which includes a supporting layer, an N-type sensitive layer and a bridge assembly, wherein the supporting layer includes a first surface and a cavity, and the cavity runs through the first surface; the N-type sensitive layer is arranged on the first surface and covers the cavity; the bridge assembly is arranged on the N-type sensitive layer and includes a plurality of P-type piezoresistors, and the plurality of P-type piezoresistors are connected in series in sequence to form a ring structure; each P-type piezoresistive element includes a first piezoresistor and a second piezoresistor connected in series, the orthographic projection of the first piezoresistor to the supporting layer at least partially overlaps with the cavity, and the orthographic projection of the second piezoresistor to the supporting layer is misaligned with the cavity, and when the piezoresistive pressure sensor is subjected to non-test pressure, the resistance value of one of the first piezoresistor and the second piezoresistor increases, and the resistance value of the other decreases.

In some embodiments, an angle is formed between the setting direction of the first varistor and the setting direction of the second varistor; so that one of the first varistor and the second varistor is configured to withstand non-test pressure laterally, and the other is configured to withstand non-test pressure longitudinally.

In some embodiments, a setting direction of the first varistor is perpendicular to a setting direction of the second varistor.

In some embodiments, a disposition direction of one of the first varistor and the second varistor is perpendicular to a sidewall closest to the N-type sensitive layer.

In some embodiments, the piezoresistive pressure sensor further includes a voltage bias component, which includes a doped transition layer and a conductor, wherein the conductor, the doped transition layer and the N-type sensitive layer are connected in sequence, and the conductor is connected to the high potential of the piezoresistive pressure sensor.

In some embodiments, the voltage bias component is disposed on a surface of the N-type sensitive layer facing away from the support layer.

In some embodiments, the voltage bias component is ring-shaped, and the shape of the voltage bias component is the same as the outer contour of the N-type sensitive layer.

In some embodiments, the doped transition layer includes a first doped layer and a second doped layer, and the N-type sensitive layer, the first doped layer, the second doped layer and the conductor are connected in sequence; the doping concentration of the N-type sensitive layer, the doping concentration of the first doped layer and the doping concentration of the second doped layer increase gradually.

In some embodiments, a disposition direction of the first varistor is perpendicular to a disposition direction of the second varistor, and a disposition direction of one of the first varistor and the second varistor is perpendicular to a closest conductor.

In some embodiments, the normal resistance of the first varistor is R1, the normal resistance of the second varistor is R2, the shortest distance between the first varistor and the conductor is L1, the shortest distance between the second varistor and the conductor is L2, then R1L1=R2L2.

In some embodiments, the piezoresistive pressure sensor also includes a shielding layer, which is arranged on the side of the N-type sensitive layer away from the supporting layer, and the positive projections of the first piezoresistor and the second piezoresistor to the shielding layer fall on the shielding layer, and the shielding layer is connected to the high potential of the piezoresistive pressure sensor.

In some embodiments, the piezoresistive pressure sensor further includes an insulating layer, and the insulating layer is disposed on a side of the N-type sensitive layer close to the supporting layer.

An embodiment of the present invention further provides an electronic device, which includes the piezoresistive pressure sensor provided by any of the above embodiments.

The technical solution of the present invention is to set a P-type piezoresistive element including a first piezoresistance and a second piezoresistance connected in series, wherein the orthographic projection of the first piezoresistance to the supporting layer at least partially overlaps with the cavity, and the orthographic projection of the second piezoresistance to the supporting layer is misaligned with the cavity, so that when the piezoresistive pressure sensor is working normally, the first piezoresistance can be used to normally sense pressure, and the resistance value of the second piezoresistance will not be affected; when the P-type piezoresistive element is subjected to non-test pressure, the resistance value of one of the first piezoresistance and the second piezoresistance increases, and the resistance value of the other decreases, thereby reducing the resistance change of the P-type piezoresistive element when it is affected by the non-test pressure, reducing the influence of the non-test pressure on the resistance value of the P-type piezoresistive element, and improving the measurement accuracy of the piezoresistive pressure sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

FIG1 is a top view of a piezoresistive pressure sensor provided by one embodiment of the present invention;

FIG2 is a cross-sectional view of the piezoresistive pressure sensor shown in FIG1 along line A-A;

FIG3 is an enlarged view of part B of the piezoresistive pressure sensor shown in FIG2 ;

FIG. 4 is a schematic diagram of circuit connections of a piezoresistive pressure sensor according to an embodiment of the present invention.

Description of Figure Numbers:

100, piezoresistive pressure sensor; 10, supporting layer; 11, first surface; 12, cavity; 20, N-type sensitive layer; 30, bridge assembly; 31, P-type piezoresistive element; 311, first varistor; 312, second varistor; 40, voltage bias assembly; 41, doped transition layer; 411, first doped layer; 412, second doped layer; 42, conductor; 50, shielding layer; 60, insulating layer;

101, a first P-type piezoresistive element; 102, a second P-type piezoresistive element; 103, a third P-type piezoresistive element; 104, a fourth P-type piezoresistive element.

The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings.

DETAILED DESCRIPTION

The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

Piezoresistive pressure sensors have the characteristics of small size, light weight, easy integration, ultra-high sensitivity and resolution, and are widely used in various fields such as aerospace, aviation, biomedicine, meteorology, geology, and seismic measurement.

The piezoresistive sensor chip of the related technology is sensitive to the charges introduced by the environment and packaging. When external charges gather on the chip surface, they easily form a leakage path with the substrate through the doped area. In this regard, the related technology usually adopts the substrate voltage bias method to form a reverse biased PN junction, thereby improving the leakage problem.

However, the use of substrate voltage bias inevitably places a conductive conductor part in the substrate part of the chip. When in use, due to the difference in thermal expansion coefficients between the aforementioned conductor part and the silicon material of the substrate, the stress at the piezoresistor position of the chip changes during temperature changes, which in turn affects the output result of the pressure test; similarly, during the packaging process of the piezoresistive pressure sensor, pressure may be exerted on the N-type sensitive layer inside the piezoresistive pressure sensor, thereby causing the normal resistance value of the P-type piezoresistive component used for measurement to change, which will also affect the output result of the pressure test and thus affect the accuracy of the pressure measurement result.

Based on this, the present invention aims to provide a new piezoresistive pressure sensor to reduce the influence of deformation caused by non-test pressure on the internal P-type piezoresistive element when subjected to non-test pressure, thereby improving the measurement accuracy of the piezoresistive pressure sensor.

1 to 3, an embodiment of the present invention provides a piezoresistive pressure sensor 100, which includes a support layer 10, an N-type sensitive layer 20, and a bridge assembly 30, wherein the support layer 10 includes a first surface 11 and a cavity 12, and the cavity 12 penetrates the first surface 11; the N-type sensitive layer 20 is disposed on the first surface 11 and covers the cavity 12; the bridge assembly 30 is disposed on the N-type sensitive layer 20 and includes a plurality of P-type piezoresistors 31, and the plurality of P-type piezoresistors 31 are disposed on the N-type sensitive layer 20. The resistors 31 are connected in series in sequence to form a ring structure; each P-type piezoresistive element 31 includes a first piezoresistance 311 and a second piezoresistance 312 connected in series, the orthographic projection of the first piezoresistance 311 to the support layer 10 at least partially overlaps with the cavity 12, and the orthographic projection of the second piezoresistance 312 to the support layer 10 is misaligned with the cavity 12. When the piezoresistive pressure sensor 100 is subjected to non-test pressure, the resistance of one of the first piezoresistance 311 and the second piezoresistance 312 increases, and the resistance of the other decreases.

The piezoresistive pressure sensor 100 is a component formed by the piezoresistive effect of single crystal silicon and is used to sense external pressure. When the external pressure changes, the single crystal silicon is strained, causing the strain resistor set in the single crystal silicon to produce a deformation proportional to the measured pressure, thereby obtaining a corresponding voltage output signal.

The function of the support layer 10 is to provide support for the N-type sensitive layer 20 and the bridge component 30 disposed on the N-type sensitive layer 20. In these embodiments of the present invention, the support layer 10 can be set to a silicon structure to facilitate the formation of the support layer 10 and improve the consistency of the structural strength between the support layer 10 and the N-type sensitive layer 20, thereby forming a more stable support for the N-type sensitive layer 20.

In these embodiments of the present invention, the piezoresistive pressure sensor 100 may be an absolute pressure sensor, and in some embodiments, may also be a differential pressure sensor. The present invention is described only by taking the piezoresistive pressure sensor 100 as an absolute pressure sensor as an example.

Based on this, the supporting layer 10 includes a first surface 11 and a cavity 12, and the cavity 12 penetrates the first surface 11 so that the supporting layer 10 forms a structure with an opening at one end. At this time, the N-type sensitive layer 20 is arranged on the first surface 11 and covers the cavity 12, so that the side of the N-type sensitive layer 20 away from the cavity 12 is the air intake side, and the side close to the cavity 12 is the vacuum side, thereby forming the structure of an absolute pressure sensor.

In some embodiments, the cavity 12 may be arranged to penetrate the first surface 11 while penetrating the surface of the support layer 10 opposite to the first surface 11, thereby forming a structure that allows air to enter at both ends. In this case, the piezoresistive pressure sensor 100 is a differential pressure sensor.

The N-type sensitive layer 20 may be a film layer disposed on the first surface 11 of the support layer 10 , so as to facilitate the arrangement of the aforementioned bridge component 30 and wiring therein.

The bridge assembly 30 is arranged on the N-type sensitive layer 20 and includes a plurality of P-type piezoresistors 31, which are connected in series to form a ring structure. A possible implementation method is that the plurality of P-type piezoresistors 31 of the bridge assembly 30 are connected in series to form a Wheatstone bridge. At this time, when the external pressure acts on the N-type sensitive layer 20 through the cavity 12, the relative position of the N-type sensitive layer 20 and the cavity 12 will be deformed, and when the stress generated by such deformation acts on each P-type piezoresistor 31, the resistance value of each P-type piezoresistor 31 will change, thereby causing the imbalance of the Wheatstone bridge. At this time, the pressure detection can be achieved by detecting the difference in the output of the Wheatstone bridge.

In these embodiments of the present invention, each P-type piezoresistor 31 is provided to include a first piezoresistor 311 and a second piezoresistor 312 connected in series, and it is further provided that the orthographic projection of the first piezoresistor 311 onto the supporting layer 10 at least partially overlaps with the cavity 12, and the orthographic projection of the second piezoresistor 312 onto the supporting layer 10 is misaligned with the cavity 12, which means that the first piezoresistor 311 is a normal operating resistor in the P-type piezoresistor 31, and the second piezoresistor 312 is a balancing resistor in the P-type piezoresistor 31 for balancing the resistance value of the first piezoresistor 311.

In this way, during the normal operation of the pressure test, the second varistor 312 is not easily affected by the stress generated by the deformation of the N-type sensitive layer 20. Therefore, the second varistor 312 will not affect the test during normal operation. The first varistor 311 deforms after sensing the stress applied by the N-type sensitive layer 20, thereby causing a change in resistance value, and finally realizing pressure detection.

When the piezoresistive pressure sensor 100 is subjected to non-test pressure, for example, when the piezoresistive pressure sensor 100 is subjected to stress during packaging, both the first piezoresistors 311 and the second piezoresistors 312 can sense changes in stress. At this time, the resistance of one of the first piezoresistors 311 and the second piezoresistors 312 increases, while the resistance of the other decreases, so as to reduce the overall resistance change of the P-type piezoresistive element 31, thereby improving the stability and reliability of the bridge assembly 30, and further improving the measurement accuracy of the piezoresistive pressure sensor 100.

Non-test pressure refers to the pressure used for testing the non-piezoresistive pressure sensor 100, which is the pressure that inevitably acts on the N-type sensitive layer 20, such as the packaging stress generated during the packaging process of the piezoresistive pressure sensor 100, or the thermal stress generated due to the difference in thermal expansion coefficients between components when the piezoresistive pressure sensor 100 generates heat during operation, etc.

When the piezoresistive pressure sensor 100 is subjected to non-test pressure, the resistance of one of the first piezoresistors 311 and the second piezoresistors 312 increases, and the resistance of the other decreases, which means that when the P-type piezoresistors 31 are subjected to non-test pressure, both the first piezoresistors 311 and the second piezoresistors 312 will be deformed, and in the stress direction generated by the non-test pressure, the placement direction and relative position relationship of the first piezoresistors 311 and the second piezoresistors 312 are designed so that the resistance of one of the first piezoresistors 311 and the second piezoresistors 312 becomes smaller, and at the same time, the resistance of the other increases. In this way, the overall resistance change of the first piezoresistors 311 and the second piezoresistors 312 can be reduced, thereby improving the accuracy of the result output during normal operation.

In these embodiments of the present invention, the first varistor 311 and the second varistor 312 can be set as varistor with the same normal resistance and the same product size. For example, the first varistor 311 and the second varistor 312 can be set as varistor formed by P-type doping. In this way, since the first varistor 311 and the second varistor 312 are the same varistor, it is beneficial to balance the resistance change when the two are subjected to non-test pressure by controlling the relative position relationship between the two.

The technical solution of the present invention is to set a P-type piezoresistive element 31 including a first piezoresistance 311 and a second piezoresistance 312 connected in series, wherein the orthographic projection of the first piezoresistance 311 onto the supporting layer 10 at least partially overlaps with the cavity 12, and the orthographic projection of the second piezoresistance 312 onto the supporting layer 10 is misaligned with the cavity 12, so that when the piezoresistive pressure sensor 100 is working normally, the first piezoresistance 311 can be used to normally sense pressure, and the resistance value of the second piezoresistance 312 will not be affected; when the P-type piezoresistive element 31 is subjected to non-test pressure, the resistance value of one of the first piezoresistance 311 and the second piezoresistance 312 increases, and the resistance value of the other decreases, thereby reducing the resistance change of the P-type piezoresistive element 31 when it is affected by the non-test pressure, reducing the influence of the non-test pressure on the resistance value of the P-type piezoresistive element 31, and improving the measurement accuracy of the piezoresistive pressure sensor 100.

In some embodiments, an angle is formed between the setting direction of the first piezoresistor 311 and the setting direction of the second piezoresistor 312; so that one of the first piezoresistor 311 and the second piezoresistor 312 is configured to withstand non-test pressure laterally, and the other is configured to withstand non-test pressure longitudinally.

One of the first varistor 311 and the second varistor 312 is configured to withstand non-test pressure in the transverse direction, wherein the transverse direction refers to a direction perpendicular to the current flow direction, and the resistance value of the varistor will decrease; the other is configured to withstand non-test pressure in the longitudinal direction, wherein the longitudinal direction refers to a direction parallel to the current flow direction, and the resistance value of the varistor will increase. In this way, by designing the setting directions of the first varistor 311 and the second varistor 312, when the two are subjected to non-test pressure, the resistance value of one increases and the resistance value of the other decreases.

In these embodiments of the present invention, the stress direction generated by the non-test pressure can be determined during the design stage of the piezoresistive pressure sensor 100, and then during the production stage of the piezoresistive pressure sensor 100, the setting directions of the first piezoresistors 311 and the second piezoresistors 312 can be adjusted so that one of them bears the non-test pressure laterally and the other bears the non-test pressure longitudinally.

For example, in some embodiments, the first piezoresistor 311 may be configured to bear non-test pressure in the horizontal direction, and the second piezoresistor 312 may be configured to bear non-test pressure in the vertical direction. In this way, when the first piezoresistor 311 is subjected to non-test pressure, the resistance decreases; at the same time, when the second piezoresistor 312 is subjected to non-test pressure, the resistance increases.

Based on this, when the bridge assembly 30 is subjected to non-test pressure, each P-type piezoresistive element 31 can use the second piezoresistor 312 to balance the resistance change of the first piezoresistor 311 when subjected to non-test pressure, thereby reducing the overall change in resistance of each P-type piezoresistive element 31 when subjected to non-test pressure, thereby improving the test accuracy of the piezoresistive pressure sensor 100.

Furthermore, an angle is formed between the setting direction of the first piezoresistors 311 and the setting direction of the second piezoresistors 312, which means that after determining the stress direction generated by the non-test pressure, an angle is formed between the setting direction of the first piezoresistors 311 and the setting direction of the second piezoresistors 312, so that when each P-type piezoresistive element 31 is subjected to non-test pressure, the same non-test pressure will cause one of the two to bear the stress generated by the non-test pressure laterally, and the other to bear the stress generated by the non-test pressure longitudinally.

For example, in an embodiment where the effect of packaging stress on each P-type piezoresistive element 31 needs to be considered, since the direction of the stress generated during packaging can be regarded as being perpendicular to the direction inward of the side wall, at this time, the angle between the first piezoresistance 311 and the stress direction generated by packaging can be set to be greater than 45°, so that when the first piezoresistance 311 is under pressure, it is more likely to withstand non-test pressure in the lateral direction; at the same time, the angle between the second piezoresistance 312 and the stress direction generated by packaging can be set to be less than 45°, so that when the second piezoresistance 312 is under pressure, it is more likely to withstand non-test pressure in the longitudinal direction.

In some embodiments, the arrangement direction of the first varistor 311 is perpendicular to the arrangement direction of the second varistor 312 .

In this way, it is beneficial to improve the balance control of the first piezoresistance 311 and the second piezoresistance 312 when each P-type piezoresistive element 31 is subjected to non-test pressure, further reduce the overall resistance change of each P-type piezoresistive element 31, and even achieve a situation where the resistance value of each P-type piezoresistive element 31 does not change when subjected to non-test pressure.

In these embodiments of the present invention, the setting direction of the first varistor 311 is perpendicular to the setting direction of the second varistor 312, that is, there is a symmetry axis between the first varistor 311 and the second varistor 312. When designing the positions of the first varistor 311 and the second varistor 312, as long as it is noted that there is an angle between the setting of the aforementioned symmetry axis and the stress direction generated by the foreseeable non-test pressure, it can be achieved that when each P-type piezoresistive element 31 is subjected to non-test pressure, one of the first varistor 311 and the second varistor 312 is subjected to non-test pressure in the horizontal direction, and the other is subjected to non-test pressure in the longitudinal direction.

In some embodiments, a disposition direction of one of the first varistor 311 and the second varistor 312 is perpendicular to the closest sidewall of the N-type sensitive layer 20 .

The setting direction is perpendicular to the side wall closest to the N-type sensitive layer 20, so as to control the setting of one of the first piezoresistors 311 and the second piezoresistors 312 to be parallel to the foreseeable packaging stress, and at the same time, the other is perpendicular to the packaging stress. In this way, when each P-type piezoresistor 31 is subjected to the stress generated during packaging, the stress is applied perpendicular to the end face of one of the first piezoresistors 311 and the second piezoresistors 312, so that the resistor is subjected to non-test pressure in the longitudinal direction; at the same time, the stress is applied perpendicular to the side of the other, so that the resistor is subjected to non-test pressure in the transverse direction, and there is no component force in other directions. The resistance balance ability of the P-type piezoresistors 31 when subjected to non-test pressure is further improved, and the reliability is better.

In these embodiments of the present invention, since there are multiple P-type piezoresistors 31 and the stress generated by the package can be foreseen to be perpendicular to the side wall of the N-type sensitive layer 20, when each P-type piezoresistor 31 is set, the resistance balance ability of the P-type piezoresistor 31 when subjected to non-test pressure can be further improved by setting one of the first piezoresistors 311 and the second piezoresistors 312 perpendicular to the side wall closest to the N-type sensitive layer 20.

Exemplarily, in an embodiment in which the shape of the N-type sensitive layer 20 is a rectangular body, four P-type piezoresistors 31 can be set, and the four P-type piezoresistors 31 are respectively arranged close to the four side walls of the N-type sensitive layer 20, and in each P-type piezoresistor 31, the setting direction of one of the first piezoresistors 311 and the second piezoresistors 312 is perpendicular to the side wall closest to the N-type sensitive layer 20.

In an embodiment in which the N-type sensitive layer 20 is shaped like a cylinder, in each P-type piezoresistive element 31, the setting direction of one of the first piezoresistors 311 and the second piezoresistors 312 can be arranged perpendicular to the nearest tangent, so that the setting direction of one of the first piezoresistors 311 and the second piezoresistors 312 is parallel to the stress direction generated by the foreseeable non-test pressure, and the other is perpendicular to the stress direction generated by the foreseeable non-test pressure.

In some embodiments, the piezoresistive pressure sensor 100 also includes a voltage bias component 40, which includes a doped transition layer 41 and a conductor 42. The conductor 42, the doped transition layer 41 and the N-type sensitive layer 20 are connected in sequence, and the conductor 42 is connected to the high potential of the piezoresistive pressure sensor 100.

The function of the voltage bias component 40 is to connect the N-type sensitive layer 20 as the substrate to a high potential, thereby forming a reverse biased PN junction to improve the problem that when external charges gather on the surface of the piezoresistive pressure sensor 100, they easily form a leakage path through the substrate.

In these embodiments of the present invention, a conductor 42 is provided to connect the high potential of the piezoresistive pressure sensor 100 , and the N-type sensitive layer 20 is connected to the conductor 42 via the doped transition layer 41 , thereby connecting the N-type sensitive layer 20 to the high potential of the piezoresistive pressure sensor 100 .

The doped transition layer 41 is disposed as an intermediate medium between the conductor 42 and the N-type sensitive layer 20, and plays a role in increasing the conductivity, thereby improving the electrical connection performance between the conductor 42 and the N-type sensitive layer 20. In these embodiments of the present invention, the N-type sensitive layer 20 can be set as an N-type silicon film, the doped transition layer 41 is N-type doped, and the doping concentration of the doped transition layer 41 is higher than the doping concentration of the N-type sensitive layer 20.

The conductor 42 , the doped transition layer 41 and the N-type sensitive layer 20 are connected in sequence, which means that the conductor 42 , the doped transition layer 41 and the N-type sensitive layer 20 form a stacked structure.

In some embodiments, the voltage bias component 40 may be configured as a block structure and disposed at a location in the piezoresistive pressure sensor 100 where charge concentration is likely to occur, thereby forming a leakage path.

In some embodiments, the voltage bias component 40 may also be set as a ring structure, wherein the doped transition layer 41 is connected to the side wall of the N-type sensitive layer 20 along the outer contour of the N-type sensitive layer 20, and the conductor 42 is arranged on the outside of the doped transition layer 41 away from the N-type sensitive layer 20.

In some embodiments, the voltage bias component 40 is disposed on the surface of the N-type sensitive layer 20 away from the support layer 10. In this way, compared with the aforementioned implementation in which the voltage bias component 40 is disposed around the side wall of the N-type sensitive layer 20, the stability of the voltage bias component 40 can be increased, and the N-type sensitive layer 20 can provide a better support effect for the voltage bias component 40.

In these embodiments of the present invention, the material of the conductor 42 may be, but is not limited to, metals such as aluminum, copper, or other materials with good electrical conductivity.

When the N-type doped N-type sensitive layer 20 forms a high potential by connecting to the voltage bias component 40, it can form a reverse biased PN junction with each P-type piezoresistive element 31, thereby reducing the probability of leakage of the piezoresistive pressure sensor 100, reducing the influence of the leakage phenomenon on the test accuracy of the piezoresistive pressure sensor 100, and thereby improving the test accuracy of the piezoresistive pressure sensor 100.

In some embodiments, the voltage bias component 40 can be configured to be a ring structure having the same outer contour as the N-type sensitive layer 20 . This can improve the uniformity of the voltage bias component 40 distributed throughout the N-type sensitive layer 20 and provide higher reliability.

In some embodiments, the doped transition layer 41 includes a first doped layer 411 and a second doped layer 412, and the N-type sensitive layer 20, the first doped layer 411, the second doped layer 412 and the conductor 42 are connected in sequence; the doping concentration of the N-type sensitive layer 20, the doping concentration of the first doped layer 411 and the doping concentration of the second doped layer 412 increase gradually.

In these embodiments of the present invention, the doping concentration of the N-type sensitive layer 20, the doping concentration of the first doping layer 411 and the doping concentration of the second doping layer 412 are gradually increased, so that the conductivity of the N-type sensitive layer 20, the first doping layer 411 and the second doping layer 412 is gradually increased, which is beneficial to improving the electrical connection effect between the conductor 42 and the N-type sensitive layer 20.

In some embodiments, the arrangement direction of the first varistor 311 is perpendicular to the arrangement direction of the second varistor 312 , and the arrangement direction of one of the first varistor 311 and the second varistor 312 is perpendicular to the closest conductor 42 .

Since the material of the conductor 42 and the N-type sensitive layer 20 are different, the thermal expansion coefficients of the two are different. During the operation of the piezoresistive pressure sensor 100, the conductor 42 and the N-type sensitive layer 20 expand due to heat, and a non-test pressure is formed due to the difference in thermal stress.

In these embodiments of the present invention, similar to coping with the non-test pressure caused by packaging stress, the resistance balancing ability of the P-type piezoresistive element 31 when subjected to non-test pressure caused by thermal stress differences is improved by setting one of the first piezoresistors 311 and the second piezoresistors 312 perpendicular to the nearest conductor 42.

In an embodiment where the shape of the voltage bias component 40 is a ring structure with the same outer contour shape as the N-type sensitive layer 20, the directions of the non-test pressures generated by the different packaging stresses and thermal stresses can be controlled to be similar. At this time, the structure is beneficial for simultaneously solving the test accuracy impact caused by the two non-test pressures.

In some embodiments, the normal resistance of the first varistor 311 is R1, the normal resistance of the second varistor 312 is R2, the shortest distance between the first varistor 311 and the conductor 42 is L1, and the shortest distance between the second varistor 312 and the conductor 42 is L2, then R1L1=R2L2.

In these embodiments of the present invention, by making differentiated designs for the normal resistance value of the first varistor 311 and the normal resistance value of the second varistor 312, the accuracy of the positions of the first varistor 311 and the second varistor 312 in the N-type sensitive layer 20 can be improved, so that when the P-type piezoresistive element 31 responds to non-test pressure caused by thermal stress differences, the overall resistance change of the P-type piezoresistive element 31 is further reduced, and even the effect of the overall resistance remaining unchanged is achieved, thereby further improving the test accuracy of the piezoresistive pressure sensor 100.

In some embodiments, the piezoresistive pressure sensor 100 also includes a shielding layer 50, which is arranged on the side of the N-type sensitive layer 20 away from the supporting layer 10, and the positive projections of the first piezoresistor 311 and the second piezoresistor 312 onto the shielding layer 50 fall on the shielding layer 50, and the shielding layer 50 is connected to the high potential of the piezoresistive pressure sensor 100.

The shielding layer 50 is connected to the high potential of the piezoresistive pressure sensor 100, and the shielding layer 50 is arranged on the side of the N-type sensitive layer 20 away from the supporting layer 10. In this way, the charges that may be accumulated on the surface of the N-type sensitive layer 20 away from the supporting layer 10 can be promptly conducted away, thereby reducing the accumulation of charges on the surface of the N-type sensitive layer 20 away from the supporting layer 10.

At the same time, by setting the orthographic projections of the first piezoresistor 311 and the second piezoresistor 312 onto the shielding layer 50 to fall on the shielding layer 50, the influence of charge accumulation on the first piezoresistor 311 or the second piezoresistor 312 can be further reduced, thereby further improving the test accuracy of the piezoresistive pressure sensor 100.

In these embodiments of the present invention, the shielding layer 50 may be made of polysilicon material or other materials with conductive properties.

In some embodiments, the piezoresistive pressure sensor 100 further includes an insulating layer 60 , which is disposed on a side of the N-type sensitive layer 20 close to the supporting layer 10 to improve the insulation performance between the N-type sensitive layer 20 and the supporting layer 10 .

Please refer to Figures 1 to 4 in detail. Figure 4 shows an embodiment of the bridge assembly 30 of the present invention, which is composed of four P-type piezoresistors 31 (bridge arms) connected in series to form a Wheatstone bridge. The four P-type piezoresistors 31 are respectively defined as a first P-type piezoresistor 101, a second P-type piezoresistor 102, a third P-type piezoresistor 103 and a fourth P-type piezoresistor 104.

Based on this, during normal use of the piezoresistive pressure sensor 100 provided by the present invention, a pad connected to a high potential VDD can be set between the first P-type piezoresistive element 101 and the second P-type piezoresistive element 102, and a pad connected to a low potential GND can be set between the third P-type piezoresistive element 103 and the fourth P-type piezoresistive element 104. When the pressure to be measured is applied to the surface of the piezoresistive pressure sensor 100, the position of the N-type sensitive layer 20 corresponding to the cavity 12 will be deformed, thereby applying stress to the first piezoresistor 311, causing the resistance value of the first piezoresistor 311 to change.

At this time, pads can be set between the first P-type piezoresistor 101 and the fourth P-type piezoresistor 104, and between the second P-type piezoresistor 102 and the third P-type piezoresistor 103, and the pressure value can be detected by detecting the voltage output change between the two pads.

An embodiment of the present invention further provides an electronic device, which includes the piezoresistive pressure sensor 100 provided in any of the above embodiments.

The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly/indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims (13)

1. A piezoresistive pressure sensor, comprising: A support layer, comprising a first surface and a cavity, wherein the cavity penetrates the first surface; An N-type sensitive layer, disposed on the first surface and covering the cavity; A bridge assembly, disposed in the N-type sensitive layer and comprising a plurality of P-type piezoresistors, wherein the plurality of P-type piezoresistors are sequentially connected in series to form a ring structure; Each of the P-type piezoresistors comprises a first piezoresistor and a second piezoresistor connected in series, wherein an orthographic projection of the first piezoresistor onto the support layer at least partially overlaps with the cavity, and an orthographic projection of the second piezoresistor onto the support layer is misaligned with the cavity, The P-type piezoresistive element is used to increase the resistance of one of the first piezoresistance and the second piezoresistance and decrease the resistance of the other one when subjected to non-test pressure. 2. The piezoresistive pressure sensor according to claim 1, wherein an angle is formed between a setting direction of the first piezoresistors and a setting direction of the second piezoresistors; So that one of the first varistor and the second varistor is configured to withstand non-test pressure in the transverse direction, and the other is configured to withstand non-test pressure in the longitudinal direction. 3 . The piezoresistive pressure sensor according to claim 2 , wherein a setting direction of the first piezoresistors is perpendicular to a setting direction of the second piezoresistors. 4 . The piezoresistive pressure sensor according to claim 3 , wherein a setting direction of one of the first piezoresistors and the second piezoresistors is perpendicular to a side wall closest to the N-type sensitive layer. 5. The piezoresistive pressure sensor according to claim 1, characterized in that the piezoresistive pressure sensor further comprises: The voltage bias component comprises a doped transition layer and a conductor, wherein the conductor, the doped transition layer and the N-type sensitive layer are connected in sequence, and the conductor is connected to the high potential of the piezoresistive pressure sensor. 6 . The piezoresistive pressure sensor according to claim 5 , wherein the voltage bias component is arranged on a surface of the N-type sensitive layer facing away from the supporting layer. 7 . The piezoresistive pressure sensor according to claim 5 , wherein the voltage bias component is ring-shaped, and the shape of the voltage bias component is the same as the outer contour of the N-type sensitive layer. 8. The piezoresistive pressure sensor according to claim 5, wherein the doped transition layer comprises a first doped layer and a second doped layer, and the N-type sensitive layer, the first doped layer, the second doped layer and the conductor are connected in sequence; The doping concentration of the N-type sensitive layer, the doping concentration of the first doping layer, and the doping concentration of the second doping layer are gradually increased. 9. The piezoresistive pressure sensor according to claim 5, characterized in that a setting direction of the first piezoresistors is perpendicular to a setting direction of the second piezoresistors, and a setting direction of one of the first piezoresistors and the second piezoresistors is perpendicular to the closest conductor. 10. The piezoresistive pressure sensor according to claim 9, characterized in that a normal resistance value of the first piezoresistor is R1, a normal resistance value of the second piezoresistor is R2, a shortest distance between the first piezoresistor and the conductor is L1, a shortest distance between the second piezoresistor and the conductor is L2, and then R1L1=R2L2. 11. The piezoresistive pressure sensor according to claim 1 is characterized in that the piezoresistive pressure sensor also includes a shielding layer, the shielding layer is arranged on the side of the N-type sensitive layer away from the supporting layer, the orthographic projections of the first piezoresistor and the second piezoresistor to the shielding layer fall on the shielding layer, and the shielding layer is connected to the high potential of the piezoresistive pressure sensor. 12 . The piezoresistive pressure sensor according to claim 1 , further comprising an insulating layer, wherein the insulating layer is disposed on a side of the N-type sensitive layer close to the supporting layer. 13. An electronic device, comprising the piezoresistive pressure sensor according to any one of claims 1 to 12.