CN216899365U - Pressure sensing structure and pressure sensor - Google Patents
Pressure sensing structure and pressure sensor Download PDFInfo
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- CN216899365U CN216899365U CN202220418152.3U CN202220418152U CN216899365U CN 216899365 U CN216899365 U CN 216899365U CN 202220418152 U CN202220418152 U CN 202220418152U CN 216899365 U CN216899365 U CN 216899365U
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Abstract
The utility model discloses a pressure sensing structure and a pressure sensor, comprising: the force sensitive body comprises a supporting part and a force sensitive membrane, the force sensitive membrane is arranged above the supporting part, the force sensitive membrane is provided with a deformable area and an undeformable area, and the supporting part is fixedly connected with the force sensitive membrane; the piezoresistor is arranged on the force sensitive body; the piezoresistors comprise a first group of piezoresistors and a second group of piezoresistors, the first group of piezoresistors are arranged on the deformable area of the force sensitive film and form a first Wheatstone bridge, and the second group of piezoresistors are arranged on the non-deformable area of the force sensitive film and form a second Wheatstone bridge. The utility model provides a pressure sensing structure and a pressure sensor, and aims to effectively solve the technical problems that in the prior art, the zero temperature characteristic of the sensor is influenced due to different thermal expansion coefficients of different parts of the pressure sensor, and the measurement precision is influenced due to the fact that a force sensitive membrane is easy to generate nonlinear deformation under strong pressure.
Description
Technical Field
The utility model relates to the technical field of sensors, in particular to a pressure sensing structure and a pressure sensor.
Background
At present, electronic products are developed towards the intelligent direction more and more, and a sensor plays an important role in the using process of the electronic products as information acquisition equipment. Among them, the demand for pressure sensors to measure stress or pressure is increasing year by year. In order to meet the requirements of various electronic products, some special requirements are provided for the pressure sensor, the pressure sensor can effectively transmit acting force to a film of a chip, parts on the chip are protected from being damaged, and the sensor is further required to keep a smaller size so as to meet the requirement of the electronic products on portability.
Most piezoresistor sensing parts of the pressure sensor are formed by diffusion or ion implantation, and the piezoresistor sensing parts have the defect that the zero point changes along with the temperature, because the silicon substrate and the parts on the silicon substrate are made of different materials, and the corresponding thermal expansion coefficients are different. Meanwhile, different assembling materials have different thermal expansion coefficients in the assembling process, and influence is caused on the zero temperature characteristic of the pressure sensor, so that the measuring result of the sensor is deviated. In addition, the chip film thickness of the film-based pressure sensor is usually less than tens of micrometers, when a force acts on the film, the film deforms, the deformation amount of the film increases along with the increase of the force, but when the film deforms to a certain degree, the film enters a nonlinear area, the measurement precision is influenced, and the film is seriously deformed and even cracked. In order to improve the zero-temperature characteristic and the high-pressure resistance of the temperature sensor, a pressure sensor with high sensitivity, high linearity, high reliability and small zero-point temperature coefficient is required to be provided.
SUMMERY OF THE UTILITY MODEL
The utility model provides a pressure sensing structure and a pressure sensor, and aims to effectively solve the technical problems that in the prior art, the zero point temperature characteristic of the sensor is influenced due to different thermal expansion coefficients of different parts of the pressure sensor, the measurement precision is reduced, and the measurement precision is influenced due to the fact that a force sensitive membrane is easy to generate nonlinear deformation under strong pressure.
According to an aspect of the present invention, there is provided a pressure sensing structure comprising:
the force sensitive body comprises a supporting part and a force sensitive membrane and is provided with a first surface, the force sensitive membrane is arranged above the supporting part, wherein the area of the force sensitive membrane, which is not projected on the supporting part in the direction vertical to the first surface, is a deformable area of the force sensitive membrane, the area of the force sensitive membrane, which is projected on the supporting part, is an undeformable area of the force sensitive membrane, and the supporting part is fixedly connected with the force sensitive membrane;
a piezo-resistor disposed on the force sensitive body;
the piezoresistors comprise a first group of piezoresistors and a second group of piezoresistors, the first group of piezoresistors are arranged on the deformable area of the force sensitive membrane and form a first Wheatstone bridge, and the second group of piezoresistors are arranged on the non-deformable area of the force sensitive membrane and form a second Wheatstone bridge.
Further, the first surface has a groove thereon.
Further, a force-bearing carrier is disposed on the first surface of the force-sensitive body, wherein the groove forms a gap region between the force-sensitive body and the force-bearing carrier.
Further, in a direction perpendicular to the first surface, a projection of the gap area is inside a projection of the force-receiving carrier.
Further, four corner regions of one side of the force sensitive body, which faces away from the force bearing body, are recessed regions, and a part of the force sensitive body, which corresponds to the recessed regions, constitutes a deformable region of the force sensitive membrane, wherein a part of the force sensitive body, which corresponds to each recessed region, constitutes one sensitive slice of the force sensitive membrane.
Further, in a direction perpendicular to the first surface, a projection of the force-receiving carrier at least partially overlaps a projection of the deformable region of the force-sensitive membrane.
Further, the conductive link is constituted by at least one pad and a wire, wherein the at least one pad is provided on the support portion.
Further, the depth of the gap region is not less than 500 nm.
Further, the thermal expansion coefficient and the rigidity of the force bearing body are the same as or similar to those of the force sensitive body, and the force bearing body and the force sensitive body are combined in a bonding mode.
Further, the first group of piezoresistors are arranged on any two of the four sensitive pieces and are symmetrical about a perpendicular bisector of the two sensitive pieces, and the second group of piezoresistors are arranged on the non-deformable area of the force sensitive film adjacent to the other two sensitive pieces and are symmetrical about a perpendicular bisector of the other two sensitive pieces.
Further, the force sensitive film and the support portion are integrally formed.
According to another aspect of the present invention, there is provided a pressure sensor comprising a substrate and a pressure sensing structure of any of the foregoing, the pressure sensing structure being disposed on a side surface of the substrate to obtain support of the substrate.
Through one or more of the above embodiments in the present invention, at least the following technical effects can be achieved:
in the scheme of the utility model, the resistors are connected in a preset mode to form two Wheatstone bridges, one Wheatstone bridge is arranged on the force sensitive membrane which deforms after being stressed, the resistance value changes under the influence of pressure and temperature, the other Wheatstone bridge is arranged on the force sensitive membrane which does not deform after being stressed, the resistance value only changes along with the temperature, the zero drift of the piezoresistor caused by the temperature change is compensated through the differential output of the two Wheatstone bridges, the influence of the temperature on the zero point temperature characteristic is counteracted, and the temperature performance of the pressure sensing structure is improved. In the pressure sensor, the piezoresistors in the same Wheatstone bridge have the same functions, and when a sensor circuit is designed, different piezoresistors in the same Wheatstone bridge are arranged in a symmetrical mode, so that the piezoresistors at two symmetrical positions have the same pressure or temperature sensing capability. Carry out symmetrical formula overall arrangement to piezo-resistor in circuit design, can promote measurement sensitivity on the one hand, simultaneously, when different piezo-resistors atress or be heated differently, can improve measurement accuracy. In addition, when the resistors are arranged, the piezoresistors with the resistors affected by pressure and temperature are parallel or vertical to the connecting lines between the piezoresistors with the resistors affected by temperature only, namely the piezoresistors in different Wheatstone bridges are also distributed symmetrically, so that the measurement error can be effectively reduced, and the measurement accuracy of the pressure sensor is improved.
Meanwhile, the concave part is arranged on the force sensitive membrane of the pressure sensing structure, so that a gap area with a limiting effect is formed between the concave part and the stress bearing body, the problems of non-linear deformation and sensitive membrane fracture of the force sensitive membrane caused by stress can be avoided, and the reduction of the measurement precision caused by abnormal deformation is further avoided.
Drawings
The technical solution and other advantages of the present invention will become apparent from the following detailed description of specific embodiments of the present invention, which is to be read in connection with the accompanying drawings.
FIG. 1 is a front plan view of a pressure sensing structure provided in an embodiment of the present application;
FIG. 2 is a schematic diagram of a pressure sensing structure at AA' in a longitudinal section according to an embodiment of the present disclosure;
FIG. 3 is a schematic longitudinal sectional view at BB' of a pressure sensing structure provided in an embodiment of the present application;
FIG. 4 is a schematic circuit diagram of 2 Wheatstone bridges for a pressure sensing structure according to an embodiment of the present application;
FIG. 5 is a schematic diagram of a pressure sensing structure with a load-bearing body and a groove according to an embodiment of the present disclosure;
fig. 6 is a schematic view of a force-bearing body of a pressure sensing structure according to an embodiment of the present disclosure;
FIG. 7 is a front plan view of a pressure sensing structure provided in accordance with an embodiment of the present application;
fig. 8 is a front plan view of a pressure sensing structure provided in an embodiment of the present application.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the utility model, and not restrictive of the full scope of the utility model. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that, unless explicitly stated or limited otherwise, the term "and/or" herein is only one kind of association relationship describing the associated object, and means that there may be three kinds of relationships, for example, a and/or B, and may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" in this document generally indicates that the preceding and following related objects are in an "or" relationship unless otherwise specified.
As shown in fig. 1, which is a schematic view of a pressure sensing structure according to a first embodiment of the present invention, the pressure sensing structure includes:
the force sensitive body comprises a support part 1 and a force sensitive membrane 2 and is provided with a first surface, the force sensitive membrane 2 is arranged above the support part 1, wherein the area of the projection of the force sensitive membrane 2 in the direction vertical to the first surface, which does not fall on the support part 1, is a deformable area of the force sensitive membrane 2, the area of the projection, which falls on the support part 1, is an undeformable area of the force sensitive membrane 2, and the support part 1 is fixedly connected with the force sensitive membrane 2. Illustratively, as shown in fig. 1, the force sensitive body comprises two parts, the lower part is a supporting part 1 for supporting the pressure sensor, wherein the material of the supporting part 1 is a non-deformable material and does not deform under the condition of force. The force sensitive membrane 2 which can deform in partial area when the force is applied is arranged above the force sensitive body. The first surface of the force sensitive body is the upper surface, wherein, in the direction perpendicular to the first surface, the area of the force sensitive membrane 2 which does not overlap with the supporting part 1 is the deformable area, and under the normal condition, the deformation quantity on the deformable area is in a linear relation with the magnitude of the acting force. The area of the force sensitive membrane 2 overlapped with the support part 1 is an undeformable area, and on the undeformable area, the bottom of the force sensitive membrane 2 is supported by the support part 1 which can not deform, and does not deform when stressed. Wherein, the supporting part 1 and the force sensitive film 2 are fixedly connected into a whole.
A piezo-resistor disposed on the force sensitive body. For example, a plurality of different types of resistors may be provided on the force sensitive body, wherein a varistor is provided that changes in resistance as a result of deformation. The pressure sensor based on the piezoresistor is a pressure sensor manufactured by utilizing the piezoresistor effect of silicon materials and integrated circuit technology. After the silicon material is acted by force, the resistance on the sensitive core body changes, signal output is carried out through the Wheatstone bridge, finally, the change of the resistance is converted into a standard signal through an external signal processing circuit, and electric signal output which is in direct proportion to the force change can be obtained through a measuring circuit. Piezoresistors are formed by diffusion or ion implantation with a light doping, which have the disadvantage that the zero point varies with temperature, because the coefficient of thermal expansion of the silicon substrate differs from that of the different materials grown on it. Meanwhile, the thermal expansion coefficients of different assembly materials in the assembly process also affect the zero temperature characteristic of the sensor, and finally cause the performance of the pressure sensor to deviate.
The piezoresistors comprise a first group of piezoresistors and a second group of piezoresistors, the first group of piezoresistors are arranged on the deformable area of the force sensitive membrane and form a first Wheatstone bridge, and the second group of piezoresistors are arranged on the non-deformable area of the force sensitive membrane and form a second Wheatstone bridge.
Illustratively, in the present invention, the pressure sensor has a plurality of resistors thereon, and is connected via conductive links in a predetermined manner to form two wheatstone bridges, wherein the differential output of the first wheatstone bridge and the second wheatstone bridge is used for compensating the zero drift of the piezoresistor caused by temperature change. In the two wheatstone bridges, the resistance of one wheatstone bridge is influenced only by the thermal load, and the resistance of the other wheatstone bridge is influenced by both the pressure and the thermal load. The influence of temperature on the zero point can be counteracted through the measurement deviation of the two Wheatstone bridges, and the temperature compensation effect is achieved.
The piezoresistors are divided into two groups, the first group of piezoresistors is arranged on the deformable area of the force sensitive membrane 2, when the deformable area deforms, the resistance value of the piezoresistors on the first group of piezoresistors can linearly change along with the deformation of the force sensitive membrane 2, namely the magnitude of the acting force can be determined through the output of the Wheatstone bridge, and the resistance value of the resistors arranged on the non-deformable area of the force sensitive membrane 2 does not change along with the deformation of the pressure sensing structure.
Fig. 1 is a front plan view of a pressure sensing structure, where dashed lines AA 'and BB' are marked in fig. 1, fig. 2 is a schematic longitudinal section of the pressure sensing structure at AA ', and fig. 3 is a schematic longitudinal section of the pressure sensing structure at BB'. As shown in fig. 1, in the pressure sensing structure, a first piezo-resistor 41, a second piezo-resistor 42, a third piezo-resistor 51 and a fourth piezo-resistor 52 are disposed on a deformable region of the force sensing membrane 2, and these four piezo-resistors form a wheatstone bridge, and fig. 4 is a circuit diagram of the wheatstone bridge. When the deformable area of the force-sensitive membrane 2 deforms, the resistors on the membrane are driven to deform, and the resistance values of the first piezoresistor 41, the second piezoresistor 42, the third piezoresistor 51 and the fourth piezoresistor 52 are caused to change, so that the resistance values measured by the group of Wheatstone bridges are simultaneously influenced by pressure and heat load. In addition, the fifth varistor 61, the sixth varistor 62, the seventh varistor 71, and the eighth varistor 72 are provided on the non-deformable region of the force-sensitive film 2. In the schematic longitudinal section of fig. 2 and 3, the projections of the second varistor 42 and the sixth varistor 62 in the section plane overlap, and the projections of the fourth varistor 52 and the eighth varistor 72 in the section plane overlap. The four piezoresistors arranged on the non-deformable area form a further wheatstone bridge, the circuit diagram of which is shown in fig. 4. Since the four piezoresistors are arranged in the non-deformable area, the resistance value is not influenced by pressure, that is, the resistance values measured by the wheatstone bridges of the group only change along with the change of temperature, so that the zero point characteristic of the pressure sensing structure is only influenced by the thermal load. The zero drift of the piezoresistor caused by temperature change is compensated through the differential output of the two Wheatstone bridges, so that an accurate pressure measurement value can be obtained, and the temperature performance of the pressure sensing structure is improved. The four piezoresistors arranged on the deformable area of the force sensitive membrane 2 are grouped in pairs to form a group of Wheatstone bridges. Similarly, two by two pairs of four piezoresistors arranged on the non-deformable area of the force-sensitive membrane 2 form another group of Wheatstone bridges. It should be noted that, in practical applications, the connection form of the wheatstone bridge may be determined according to practical requirements, and is not limited to the resistor layout form of fig. 1 and the circuit connection form of fig. 4.
In the scheme of the utility model, the resistors are connected in a preset mode to form two Wheatstone bridges, one Wheatstone bridge is arranged on the force sensitive membrane which deforms after being stressed, the resistance value changes under the influence of pressure and temperature, the other Wheatstone bridge is arranged on the force sensitive membrane which does not deform after being stressed, the resistance value only changes along with the temperature, the zero drift of the piezoresistor caused by the temperature change is compensated through the differential output of the two Wheatstone bridges, the influence of the temperature on the zero point temperature characteristic is counteracted, and the temperature performance of the pressure sensing structure is improved. In the pressure sensor, the piezoresistors in the same Wheatstone bridge have the same functions, and when a sensor circuit is designed, different piezoresistors in the same Wheatstone bridge are arranged in a symmetrical mode, so that the piezoresistors at two symmetrical positions have the same pressure or temperature sensing capability. Carry out symmetrical formula overall arrangement to piezo-resistor in circuit design, can promote measurement sensitivity on the one hand, simultaneously, when different piezo-resistors atress or be heated differently, can improve measurement accuracy. In addition, when the resistors are arranged, the piezoresistors with the resistors affected by pressure and temperature are parallel or vertical to the connecting lines between the piezoresistors with the resistors affected by temperature only, namely the piezoresistors in different Wheatstone bridges are also distributed symmetrically, so that the measurement error can be effectively reduced, and the measurement accuracy of the pressure sensor is improved.
Further, the first surface has a groove 3 thereon. Illustratively, the first surface is an upper surface of a force sensitive body of the pressure sensing structure, as shown in fig. 3, the groove 3 is located at an upper portion of the force sensitive body, and fig. 5 is a top view of the pressure sensor provided with the groove 3.
Further, a force-bearing body 12 is arranged on the first surface of the force-sensitive body, wherein the groove 3 forms a gap region between the force-sensitive body and the force-bearing body 12. Illustratively, fig. 5 is a pressure sensor provided with a force-bearing body 12, fig. 6 is a top view of the force-bearing body 12, and the force-bearing body 12 is a whole body and covers the force-sensitive membrane 2 to act as a transmission force. When a force is applied to the force-bearing carrier 12, the force causes the force-sensitive membrane 2 to deform. Normally, the magnitude of the force and the degree of deformation are linear, but when the force sensitive membrane 2 is subjected to a strong force, non-linear deformation and membrane rupture may occur. In the scheme of the utility model, a groove 3 is arranged on the upper surface of the force sensitive body, a gap is formed between the stress bearing body 12 and the force sensitive body, and the gap area is used for limiting the deformation amount of the force sensitive membrane 2 when the stress bearing body 12 bears external pressure. The gap region may act as a limit, i.e. to control the maximum deformation of the force sensitive membrane 2. Without a limiting structure, excessive deformation of the force sensitive membrane 2 may result in non-linear deformation or rupture of the force sensitive membrane 2 as the force increases. After the limiting structure is added, the limiting structure can inhibit the maximum deformation of the force sensitive film 2, the problems of nonlinearity and sensitive film breakage caused by large deformation are avoided, and the reduction of the measurement precision due to abnormal deformation is further avoided. The force transmission of the pressure sensor is not influenced after the gap is formed, the technical effects of nonlinearity and membrane breakage caused by excessive deformation can be avoided, and the linearity and the reliability of the pressure sensor are improved.
Further, in a direction perpendicular to the first surface, a projection of the gap area is inside a projection of the load-receiving body 12. Illustratively, the gap region serves to suppress the maximum deformation of the force sensitive membrane 2, serving as a limit. In a specific layout, the projection of the gap region in the direction perpendicular to the first surface is inside the stressed carrier 12 in the direction perpendicular to the first surface, so that the technical effects of not affecting the force transmission of the pressure sensor, avoiding the nonlinearity and membrane breakage caused by large deformation, and improving the linearity and reliability of the pressure sensor can be achieved.
Further, four corner regions of a side of the force sensitive body facing away from the force bearing body 12 are recessed regions, and a portion of the force sensitive body corresponding to the recessed regions constitutes a deformable region of the force sensitive membrane 2, wherein a portion of the force sensitive body corresponding to each recessed region constitutes a sensitive slice of the force sensitive membrane 2. Illustratively, as shown in fig. 3, in the pressure sensing structure, four corner regions of a side of the force sensitive body facing away from the force bearing body 12 are all recessed regions, the pressure sensor protrudes out to form the supporting portion 1, the supporting portion 1 is in a cross shape at a middle position of the pressure sensor, and a portion of the force sensitive body corresponding to each recessed region on the periphery constitutes one sensitive segment of the force sensitive membrane 2, that is, four sensitive segments in total. After the recessed area is provided, when a force is applied to the pressure sensing structure, the force bearing body 12 transmits the force to the sensitive segment of the force sensitive membrane 2, and the pressure makes the sensitive segment generate deformation biased to the recessed area because the recessed area is arranged below the sensitive segment.
Further, in a direction perpendicular to the first surface, a projection of the force-receiving carrier 12 at least partially overlaps a projection of the deformable region of the force-sensitive membrane 2. Illustratively, the force-bearing carrier 12 overlies four sensitive segments of the force-sensitive membrane 2, as well as the groove 3.
Further, the conductive link is constituted by at least one pad and a wire, wherein the at least one pad is provided on the support portion 1. Illustratively, the pressure sensing structure has two wheatstone bridges, connect the circuit through the pad and wire, the pad is used for exporting the electric signal triggered by resistance change of the piezo-resistor to the outside, in the pressure sensing structure shown in fig. 5, the pad includes the first pad 8, the second pad 9, the third pad 10, the fourth pad 11, these four pads are all set up on the support part 1 that can not be deformed, in order to transmit the electric signal.
Further, the depth of the gap region is not less than 500 nm. For example, the size of the gap is set to be at least 500nm according to the volume of the pressure sensor in practical application, and in specific application, an operator can adjust the size of the gap according to practical situations, specifically, how much, and the utility model is not limited.
Further, the thermal expansion coefficient and the rigidity of the force bearing body 12 are the same as or similar to those of the force sensitive body, and the force bearing body 12 and the force sensitive body are combined in a bonding manner. For example, the force-bearing body 12 and the force-sensing body may be made of silicon, glass, or the like, and in order to reduce the influence of temperature on the zero point characteristic, the two materials need to be made of materials with the same or similar thermal expansion coefficients and rigidity. The influence of different materials on the zero point characteristic is also reduced as much as possible in the selection of the bonding mode, and a silicon-silicon bonding mode, a silicon-glass bonding mode or other bonding modes can be adopted.
Further, the first group of piezoresistors are arranged on any two of the four sensitive pieces and are symmetrical about a perpendicular bisector of the two sensitive pieces, and the second group of piezoresistors are arranged on the non-deformable area of the force sensitive film adjacent to the other two sensitive pieces and are symmetrical about a perpendicular bisector of the other two sensitive pieces. In the pressure sensing structure, the first group of piezoresistors are four resistors with resistance values changing along with the deformation of the force sensitive body, the four piezoresistors are respectively positioned on two sensitive segments, and the sensitive segments can deform to drive the piezoresistors to deform to cause the change of the resistance values so as to measure the pressure.
Fig. 7 is a front plan view of a pressure sensing structure provided in an embodiment of the present application, in which the first group of piezoresistors are a first piezoresistor 41, a second piezoresistor 42, a third piezoresistor 51 and a fourth piezoresistor 52. The first varistor 41 and the second varistor 42 are located on the first sensitive dice and the third varistor 51 and the fourth varistor 52 are located on the second sensitive dice. In order to minimize pressure errors sensed by piezoresistors at different positions and improve the sensitivity of the pressure sensor, the piezoresistors on the first sensitive sheet and the piezoresistors on the second sensitive sheet are symmetrically distributed about the perpendicular bisector CC' of the two sensitive sheets, and the four piezoresistors form a Wheatstone bridge with the resistance value influenced by pressure and temperature. Different resistors in the first group of piezoresistors are symmetrically distributed on the sensitive chips, and when acting force is applied to the pressure sensor, the piezoresistors positioned at the two symmetric positions have the same capability of sensing the same pressure, so that the measurement error among the different piezoresistors can be effectively reduced, and the measurement accuracy of the pressure sensor is improved.
In fig. 7, the second group of piezoresistors is a fifth piezoresistor 61, a sixth piezoresistor 62, a seventh piezoresistor 71 and an eighth piezoresistor 72. The second group of piezoresistors are arranged on the non-deformable areas of the force sensitive films corresponding to the other two sensitive sheets, wherein the fifth piezoresistor 61 and the sixth piezoresistor 62 are arranged on the non-deformable area of the force sensitive film corresponding to the third sensitive sheet, and the seventh piezoresistor 71 and the eighth piezoresistor 72 are arranged on the non-deformable area of the force sensitive film corresponding to the fourth sensitive sheet. On the pressure sensor, the vertical bisector of the third sensitive segment and the fourth sensitive segment is also a straight line CC ', the piezoresistors located on the non-deformable area corresponding to the third sensitive segment and the piezoresistors located on the non-deformable area corresponding to the fourth sensitive segment are symmetrically distributed about the vertical bisector CC' of the two sensitive segments, and the four piezoresistors form a wheatstone bridge with the resistance affected only by temperature. Different resistors in the second group of piezoresistors are symmetrically distributed on the non-deformable area of the force sensitive membrane, so that the piezoresistors at different positions have the same temperature sensing capability when the pressure sensor measures pressure, the measurement errors caused by different piezoresistors heated differently can be effectively reduced, and the measurement accuracy of the pressure sensor can be improved.
Fig. 8 is a front plan view of a pressure sensing structure according to an embodiment of the present application, in which besides the layout manner of the piezoresistors shown in fig. 7, the piezoresistors can be also laid out according to the layout manner shown in fig. 8. In fig. 8, the first group of piezoresistors is still the first group of piezoresistors, which are the first piezoresistor 41, the second piezoresistor 42, the third piezoresistor 51 and the fourth piezoresistor 52. In the layout mode of the piezoresistors, the vertical bisector of the first sensitive fragments and the second sensitive fragments is a straight line DD ', and the piezoresistors on the first sensitive fragments and the piezoresistors on the second sensitive fragments are symmetrically distributed around the straight line DD'. Similarly, the piezoresistors on the non-deformable area corresponding to the third sensitive sheet and the piezoresistors on the non-deformable area corresponding to the fourth sensitive sheet are symmetrically distributed around the straight line DD'.
In order to improve the sensitivity of pressure measurement, the layout of the piezoresistors with the same function has symmetry, and connecting lines among the piezoresistors with different functions are parallel or vertical. For example, in the pressure sensor shown in fig. 7, the connection line of the first varistor 41 and the fifth varistor 61 is parallel to the connection line of the second varistor 42 and the sixth varistor 62, and the connection line of the first varistor 41 and the eighth varistor 72 is perpendicular to the connection line of the third varistor 51 and the sixth varistor 62. It should be noted that, in practical applications, the layout of the piezoresistors can be specifically determined according to actual requirements, and is not limited to the resistor layout in fig. 7 and 8.
In the scheme of the utility model, the piezoresistors with the same function are symmetrically arranged, and the connecting lines among the piezoresistors with different functions are parallel or vertical, so that the measurement error caused by the influence of pressure and temperature on different resistors can be reduced, and the measurement sensitivity and accuracy of the pressure sensor can be improved.
Illustratively, the force-sensitive membrane 2 and the support 1 are integrally formed. I.e. the force sensitive and supporting parts 1 are different parts of one whole and are made of the same or different materials to realize the respective functions.
According to another aspect of the present invention, there is provided a pressure sensor comprising a substrate and a pressure sensing structure as described in any one of the preceding claims, the pressure sensing structure being provided on a side surface of the substrate to obtain support of the substrate.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the utility model.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the utility model. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (12)
1. A pressure sensing structure, comprising:
the force sensitive body comprises a supporting part and a force sensitive membrane and is provided with a first surface, the force sensitive membrane is arranged above the supporting part, wherein the area of the force sensitive membrane, which is not projected on the supporting part in the direction vertical to the first surface, is a deformable area of the force sensitive membrane, the area of the force sensitive membrane, which is projected on the supporting part, is an undeformable area of the force sensitive membrane, and the supporting part is fixedly connected with the force sensitive membrane;
a piezo-resistor disposed on the force sensitive body;
the piezoresistors comprise a first group of piezoresistors and a second group of piezoresistors, the first group of piezoresistors are arranged on the deformable area of the force sensitive membrane and form a first Wheatstone bridge, and the second group of piezoresistors are arranged on the non-deformable area of the force sensitive membrane and form a second Wheatstone bridge.
2. The pressure sensing structure of claim 1, wherein the first surface has a groove thereon.
3. The pressure sensing structure of claim 2, wherein a force carrier is disposed on the first surface of the force sensitive body, wherein the groove forms a gap region between the force sensitive body and the force carrier.
4. A pressure sensing structure according to claim 3, wherein a projection of the gap area is inside a projection of the load bearing body in a direction perpendicular to the first surface.
5. A pressure sensing structure according to claim 3, wherein four corner regions of a side of the force sensitive body facing away from the force bearing body are recessed regions, and a portion of the force sensitive body corresponding to the recessed regions constitutes a deformable region of the force sensitive membrane, wherein the portion of the force sensitive body corresponding to each recessed region constitutes a sensitive patch of the force sensitive membrane.
6. A pressure sensing structure according to claim 3, wherein a projection of the force-bearing body at least partially overlaps a projection of the deformable region of the force-sensitive membrane in a direction perpendicular to the first surface.
7. Pressure sensing structure according to claim 1, characterized in that the piezoresistors are connected in a predetermined manner via a conductive link consisting of at least one pad and a wire, wherein the at least one pad is provided on the support.
8. The pressure sensing structure of claim 3, wherein the depth of the interstitial regions is not less than 500 nm.
9. The pressure sensing structure of claim 3, wherein the thermal expansion coefficient and rigidity of the force bearing body are the same as or similar to those of the force sensitive body, and the force bearing body and the force sensitive body are bonded together.
10. The pressure sensing structure of claim 5, wherein the first group of piezoresistors is disposed on any two of the four sensitive segments and is symmetric about a perpendicular bisector of the two sensitive segments, and the second group of piezoresistors is disposed on the non-deformable region of the force sensitive film to which the other two sensitive segments abut and is symmetric about the perpendicular bisector of the other two sensitive segments.
11. The pressure sensing structure of claim 1, wherein the force sensitive membrane and the support portion are integrally formed.
12. A pressure sensor, characterized in that the pressure sensor comprises a substrate and a pressure sensing structure according to any of claims 1-11, which is arranged on one side surface of the substrate for obtaining support of the substrate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202220418152.3U CN216899365U (en) | 2022-02-28 | 2022-02-28 | Pressure sensing structure and pressure sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202220418152.3U CN216899365U (en) | 2022-02-28 | 2022-02-28 | Pressure sensing structure and pressure sensor |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115137517A (en) * | 2022-09-05 | 2022-10-04 | 南京湃睿半导体有限公司 | ASIC chip, sensor using same and electric toothbrush |
| CN118089996A (en) * | 2022-11-25 | 2024-05-28 | 敏之捷传感科技(常州)有限公司 | Brake force sensor for EMB control system |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115137517A (en) * | 2022-09-05 | 2022-10-04 | 南京湃睿半导体有限公司 | ASIC chip, sensor using same and electric toothbrush |
| CN118089996A (en) * | 2022-11-25 | 2024-05-28 | 敏之捷传感科技(常州)有限公司 | Brake force sensor for EMB control system |
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