CN218646480U - Piezoresistive pressure sensor - Google Patents

Abstract

The application relates to the technical field of sensing, and particularly provides a piezoresistive pressure sensor which comprises a silicon substrate and a metal lead. One side of the silicon substrate is provided with a concave structure, a silicon membrane is formed at the bottom of the concave structure, an ultra-shallow doping area is arranged on the surface of one side, away from the concave structure, of the silicon membrane, a metal lead is fixedly arranged on one side, away from the concave structure, of the silicon substrate, and at least one end of the metal lead is fixedly contacted with the ultra-shallow doping area. The ultra-shallow doped region is connected into the electric loop through a metal lead. The metal lead is prepared by magnetron sputtering or deposition. The ultra-shallow doped region is manufactured by adopting a low-energy ion implantation process. The concave structure is prepared by adopting a time division multiplexing etching technology. The utility model discloses the doping thickness in well super shallow doping district is the nanometer order of magnitude, like this in small pressure environment under the less condition of deformation volume, still can arouse great resistance value to change to realize the high sensitive detection of small pressure.

Description

Piezoresistive pressure sensor

Technical Field

The application relates to the technical field of sensing, in particular to a piezoresistive pressure sensor.

Background

The pressure sensor is a device that converts a change in pressure of a mechanical physical quantity into a swing of a pointer or an electrical physical quantity so that a pressure change that is not easily detected can be detected. According to different converted electrical physical quantities, common pressure sensors comprise a capacitance type pressure sensor and a piezoresistive type pressure sensor, the change of pressure can respectively cause the change of capacitance and resistance values, and the change of the capacitance and resistance values can be detected in a direct or indirect mode, so that the change of the pressure can be obtained; among them, piezoresistive pressure sensors are more common and have higher market share.

When the pressure to be measured is large, large pressure acts on the piezoresistive pressure sensor, deformation of a sensor diaphragm caused in the detection process is large, the piezoresistive effect is strong, the change of resistance values is large, the output value of the sensor is large, and the sensitivity is high. However, in the fields of medical sensing, industrial detection, aerospace and the like, sensing of a relatively small pressure is required, and when the piezoresistive pressure sensor is in a low-pressure environment, due to the fact that the pressure is small, deformation and stress of a sensor diaphragm caused by the pressure are low, the piezoresistive effect of the piezoresistive pressure sensor is weak, low output and low sensitivity of the piezoresistive pressure sensor are caused, and the sensing requirement cannot be met. The low sensitivity of the low voltage sensing results in distortion of the sensing result, thereby causing misjudgment and misoperation of the application equipment.

The sensitivity of the existing piezoresistive pressure sensor is improved by changing the structure of the piezoresistive pressure sensor, and if the deformation caused by tiny pressure is amplified through a complex structure, the difficulty of the manufacturing process is increased, so that the manufactured piezoresistive pressure sensor has poor consistency and low yield, and is not beneficial to industrial batch production; and the sensitivity is still low.

In summary, the conventional piezoresistive pressure sensor cannot meet the requirement of high-sensitivity sensing of minute pressure, and is not easy to be industrially produced in batch.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a piezoresistive pressure sensor to the not enough among the above-mentioned prior art. The technical conception of the utility model is as follows: the thickness of the resistor is limited to the nanometer order, namely the doping thickness of the ultra-shallow doping area is the nanometer order, so that the piezoresistive effect of the resistor is amplified, and a small deformation amount can cause a large change of the resistor.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

the application provides a piezoresistive pressure sensor, which comprises a silicon substrate and a metal lead. The Silicon substrate is made of an SOI (Silicon-On-Insulator) Silicon wafer, the metal lead is made of a metal material, and the electric circuit is communicated by utilizing the conductivity of the metal. The shape of the silicon substrate is cuboid or oblate column, and preferably, the shape of the silicon substrate is cuboid, so that the preparation is convenient and the silicon substrate is easy to integrate. One side surface of the silicon substrate is provided with a concave structure, the bottom surface of the concave structure can be rectangular or round, and preferably, the depth of the concave structure is uniform and the bottom surface is rectangular. The concave structure is prepared by adopting a time division multiplexing etching technology.

And a silicon membrane is formed at the bottom of the concave structure. The shape of the silicon membrane is the bottom shape of the concave structure, and is preferably rectangular. The thickness is in the order of microns and thus easily deformable. The surface of the silicon membrane on the side far away from the concave structure is provided with an ultra-shallow doped region, the doping depth of the ultra-shallow doped region is in a nanometer order, and the doping ions of the ultra-shallow doped region are boron ions or phosphorus ions, specifically, the types of the doping ions can be the same or different, and preferably, the types of the doping ions of the ultra-shallow doped region are the same. The ultra-shallow doped region is manufactured by adopting a low-energy ion implantation process. The shape of the metal lead can be any shape, such as a strip, a sheet and a rod. The metal lead is prepared by magnetron sputtering or deposition. The metal lead is fixedly arranged on one side of the silicon substrate far away from the concave structure. The ultra-shallow doped region is connected through a metal lead to form an electric loop, resistance change of the ultra-shallow doped region is detected, the electric loop at least comprises necessary circuit elements such as a power supply, a switch, a voltmeter, an ammeter and the like, and resistance detection can be achieved, such as resistance measurement by a voltammetry method.

Further, the number of the ultra-shallow doped regions is four, preferably, the arrangement direction is a <110> direction, and the four ultra-shallow doped regions are distributed in the stress concentration region of the silicon membrane. The four ultra-shallow doped regions are four resistors, and are connected by metal leads to form a Wheatstone bridge for detecting the change of the resistors, and the Wheatstone bridge can sensitively detect the change of the resistors.

Furthermore, above-mentioned pressure sensor is gauge pressure type sensor, the utility model discloses still disclose an absolute pressure type sensor. Specifically, glass is fixedly arranged on one side, away from the ultra-shallow doping area, of the concave structure, and a cavity is formed between the glass and the concave structure. The glass and one side of the silicon substrate layer provided with the concave structure are fixedly connected through a bonding effect, specifically, the glass and the silicon wafer are bonded together by adopting an anodic bonding technology to form a vacuum cavity, the specific size of the vacuum degree is related to the bonding process, so that a constant pressure is formed on one side of the silicon diaphragm close to the glass, and when the pressure on one side of the silicon diaphragm far away from the glass changes, the silicon diaphragm deforms, so that the deformation of the ultra-shallow doped region on the silicon diaphragm is realized, and the change of the pressure to be detected is obtained by detecting the change of the resistance due to the piezoresistive effect and the resistance change of the ultra-shallow doped region. Both sides of the gauge pressure type sensor are exposed in an environment to be measured, and only one side, far away from the concave structure, of the silicon diaphragm of the absolute pressure type sensor is exposed in the environment to be measured, so that the gauge pressure type sensor is suitable for detecting pressure change caused by pressure difference between two sides, and the absolute pressure type sensor is suitable for the environment with pressure change on one side.

Compared with the prior art, the beneficial effects of the utility model are that: the utility model discloses the doping thickness in well super shallow doping district is the nanometer order of magnitude, like this under the same deformation degree, because thickness is very little, can arouse great resistance change, under the less condition of deformation volume in the small pressure environment promptly, still can arouse great resistance change to realize the high sensitive detection of small pressure. In addition, the utility model discloses simple structure prepares easily, easily carries out batch production in the industry.

Drawings

Fig. 1 is a front view (ultra-shallow doped region side) of a piezoresistive pressure sensor provided by the present invention;

fig. 2 is a rear view (on one side of the recessed structure) of a piezoresistive pressure sensor provided by the present invention;

fig. 3 is a schematic diagram of an ultra-shallow doped region in a piezoresistive pressure sensor provided by the present invention;

fig. 4 is a simulation result of stress distribution of a silicon diaphragm in a piezoresistive pressure sensor provided by the present invention;

fig. 5 is a schematic diagram of another piezoresistive pressure sensor provided by the present invention.

Icon: 1-a silicon base layer; 11-a recessed structure; 12-ultra shallow doped region; 2-metal lead.

Detailed Description

In order to make the implementation of the present invention clearer, the following detailed description will be made with reference to the accompanying drawings.

The utility model provides a piezoresistive pressure sensor, as shown in figure 1 and figure 2, this pressure sensor includes silicon substrate 1, metal lead wire 2. The Silicon substrate 1 is made of an SOI (Silicon-On-Insulator) Silicon wafer, the metal lead 2 is made of a metal material, preferably, the metal lead 2 is made of Ti, cr or Au, and the metal is used for communicating an electric circuit by utilizing the conductivity of the metal. The shape of the silicon substrate 1 is a rectangular parallelepiped or an oblate cylindrical shape, and preferably, the shape of the silicon substrate 1 is a rectangular parallelepiped, which is convenient for preparation and easy to integrate together. Specifically, the thickness of the silicon base layer 1 is 200 to 600. Mu.m. One side surface of the silicon substrate 1 is provided with the recessed structures 11, the bottom surfaces of the recessed structures 11 may be rectangular or circular, preferably, the recessed structures 11 have uniform depth and the bottom surfaces are rectangular, specifically, the bottom surfaces may be square or rectangular with equal side length. The depth of the concave structures 11 may be uniform or non-uniform, and preferably, the depth of the concave structures 11 is uniform, so that the base number of the thickness change caused by the deformation is the same, so that the resistance change is easier to detect, otherwise, the sensitivity of some positions is higher, the sensitivity of some positions is lower, and the mutual influence between the positions is caused, so that the detection sensitivity of the resistance change is reduced. The specific dimensions of the recessed feature 11 are related to the span of the pressure sensor. The concave structure 11 is prepared by adopting a time division multiplexing method etching technology, specifically, the concave structure 11 is formed by etching the silicon substrate 1, and passivation protection and etching are alternated.

The silicon membrane is formed at the bottom of the recessed structure 11. The shape of the silicon membrane is the shape of the bottom surface of the concave structure, and preferably, the shape of the silicon membrane is rectangular or circular. The thickness of the silicon membrane is in the order of microns, preferably, the thickness of the silicon membrane needs to accord with the theory of small deflection, so that the stress change of the silicon wafer still linearly changes when the maximum measuring range is reached. The surface of the silicon membrane far away from the side of the recessed structure 11 is provided with an ultra-shallow doped region 12, and the doping depth of the ultra-shallow doped region 12 is in the order of nanometers, specifically, the doping depth is 10-30nm, and preferably, the doping depth is 20nm. The doping ions of the ultra-shallow doping region 12 are boron ions or phosphorus ions, more specifically, the types of the doping ions may be the same or different, and preferably, the types of the doping ions of the ultra-shallow doping region 12 are the same, so that the preparation is convenient, and the uneven resistance change caused by the different ion types can be avoided, so that the resistance change of the ultra-shallow doping region 12 is only related to the deformation, and the sensing sensitivity and the accuracy are improved. After doping, doping ion makes the conductivity of semiconductor increase, makes insulating super shallow doped area 12 change the P type resistance into by the insulator, and this is also the utility model discloses utilize the resistance of piezoresistive effect probing pressure. The ultra-shallow doped region 12 is manufactured by a low energy ion implantation process, and specifically, after the ion beam is emitted to the solid material, the ion beam is resisted by the solid material and slowly reduced in speed, and finally stays in the solid material, so that the ion implantation is realized.

The metal lead 2 is fixedly arranged on one side, far away from the recessed structure 11, of the silicon substrate 1, the ultra-shallow doped region 12 is connected into the electric loop through the metal lead 2, the resistance change of the ultra-shallow doped region 12 is detected, the electric loop at least comprises necessary circuit elements such as a power supply, a switch, a voltmeter and an ammeter, and the resistance detection can be achieved, for example, resistance detection through a voltammetry method is achieved. The shape of the metal lead 2 may be any shape, such as a strip, a sheet, and a rod. The metal lead wire is prepared by magnetron sputtering or deposition. During detection, the deformation of the silicon membrane changes the stress inside the ultra-shallow doped region 12, so that the resistance of the ultra-shallow doped region 12 changes, and the change of the resistance of the ultra-shallow doped region 12 is obtained through detection of an electric circuit, thereby achieving the purpose of converting mechanical physical quantity into electrical physical quantity.

As shown in fig. 3, when the doping thickness of the ultra-shallow doped region 12 is in the order of nanometers, the principle of higher sensitivity of the pressure sensor is as follows: for convenient analysis, the resistance of the ultra-shallow doped region 12 is used as a cuboid for analysis, and the expression of the resistance of the ultra-shallow doped region 12 is

Where ρ is the resistivity of the ultra-shallow doped region 12 resistor, L is the length of the ultra-shallow doped region 12 resistor, W is the width of the ultra-shallow doped region 12 resistor, and t is the thickness of the ultra-shallow doped region 12 resistor. Setting other parameters except t to be fixed, and representing the deformation of the ultra-shallow doped region 12 as the change of the thickness t, then:

wherein

Is a fixed value. Further, when the thickness t varies, the expression of the variation of the resistance R is:

wherein t is ₁ And t ₂ The thicknesses of the ultra-shallow doped regions 12 before and after the change, respectively. As can be seen from the above, when the amount of change in the thickness t is constant, the thickness t before deformation ₁ The smaller, i.e. the fingerThickness t before deformation occupied by variation ₁ Ratio of (A to B)

The larger the value of (c), and thus the larger the Δ R, the higher the sensitivity of the pressure sensor. Specifically, assuming that the deformation amount Δ t is 50nm, if the thickness t of the ultra-shallow doped region 12 before deformation is set to be 50nm ₁ 10nm, the deformation amount of t is 5 times of the original deformation amount, and the thickness t of the ultra-shallow doped region 12 before deformation ₁ For 1000nm, then the deflection of t is original 0.05 times, and the variation difference that it can arouse is huge, consequently, the utility model discloses pressure sensor's sensitivity is higher, and small deformation can arouse great resistance change promptly.

Preferably, the metal lead 2 may be in direct contact with the ultra-shallow doped region 12, or may be in contact with the ultra-shallow doped region 12 through an ohmic contact region, as shown in fig. 5, that is, the ultra-shallow doped region 12 is in fixed contact with the ohmic contact region, and the ohmic contact region is in fixed contact with the metal lead 2, so as to reduce abrupt resistance change caused by direct contact between the metal lead 2 and the ultra-shallow doped region 12, and ensure circuit conduction. Specifically, the ohmic contact region is obtained by an ion implantation method and an annealing process, specifically, the species of the implanted ions in the ohmic contact region and the species of the implanted ions in the ultra-shallow doped region 12 may be the same or different, and preferably, the species of the implanted ions in the ohmic contact region and the species of the implanted ions in the ultra-shallow doped region 12 are the same, so that the preparation is convenient; the concentration of the implanted ions in the ohmic contact region is higher than that in the ultra-shallow doped region 12, so that ohmic contact is formed and electrical connection is smooth.

Further, the ultra-shallow doped regions 12 are disposed in the stress distribution concentration region, four ultra-shallow doped regions 12 are disposed at the middle positions of the edges and near the edges, preferably, the arrangement direction is a <110> direction, so that the coefficient of the piezoresistive effect is the largest, and the piezoresistive effect is obvious, and meanwhile, the stress transmission conditions on the straight lines where the two pairs of ultra-shallow doped regions 12 are located are different, so that the resistance of the two pairs of ultra-shallow doped regions 12 is relatively changed greatly. Stress concentration district is silicon diaphragm when atress deformation, and the region that silicon diaphragm inside produced stress is big and the gathering is called stress concentration district, and four ultra-shallow adulteration districts distribute respectively in four stress concentration districts of silicon diaphragm, specifically, the shape and the size of stress concentration district are relevant with the shape and the size of silicon diaphragm, and the size change of silicon diaphragm can not change the shape in stress concentration district, only changes its area size.

Fig. 4 is a stress distribution diagram corresponding to the square silicon membrane obtained by finite element simulation calculation, wherein a dark color region indicates a region where stress changes greatly and gathers when deformed, and the darker the color indicates that the deformation is, the larger the stress change of the corresponding region is, that is, the larger the resistance change of the ultra-shallow doped region 12 arranged in the corresponding region is; when the silicon membrane is deformed, because the silicon membrane is positioned in the stress concentration area, the deformation degree of the ultra-shallow doping area 12 is larger, and the internal stress change is larger, so that larger resistance change is caused, and the sensitivity of pressure detection is improved. Since the distribution of the stress distribution region is not changed by doping, the doped region can be defined before doping, and the stress distribution after doping is also not changed, so that the ultra-shallow doped region 12 can be ensured to have a larger deformation degree, the improvement of sensitivity is ensured, and the industrial production is easy to carry out. That is, the ultra-shallow doped region 12 is disposed near the edge of the silicon membrane in the middle of the four sides. The distance from the ultra-shallow doped region 12 to the edge is less than one twentieth of the length of the edge, preferably, the distance from the ultra-shallow doped region 12 to the edge on the opposite side is the same, and the distance from the ultra-shallow doped region 12 to the edge on the adjacent side is different, so that the stress transmission conditions in two directions of the silicon membrane are different, which causes different deformations of the ultra-shallow doped region 12, i.e. different strengths of piezoresistive effect, and therefore different degrees of resistance change; more preferably, the shape of the silicon membrane is rectangular, and the distance from the two ultra-shallow doped regions 12 corresponding to the long side to the edge is smaller than the distance from the two ultra-shallow doped regions 12 corresponding to the short side to the edge, that is, the two ultra-shallow doped regions 12 corresponding to the long side are closer to the edge, because the stress concentration region corresponding to the longer side is closer to the edge, and the stress concentration region is more concentrated, the stress change in this region is larger, that is, the anisotropy of the stress transfer in the two directions of the silicon membrane is larger.

The shapes of the four ultra-shallow doped regions 12 are all rectangles, the shapes can be completely the same or not completely the same, preferably, the shapes and the sizes of opposite sides are completely the same, and due to the fact that stress concentration regions on opposite sides are symmetrical to each other, the shapes and the sizes of opposite sides are completely the same, the ultra-shallow doped regions 12 can be enabled to be in the stress concentration regions as much as possible, the areas of the stress concentration regions are the largest, resistance change caused by deformation is large, and sensing sensitivity is high. The shape of the ultra-shallow doped region 12 on the adjacent side is different, so that the ultra-shallow doped region 12 can be ensured to be in a stress concentration region while the arrangement direction is the <110> direction, and meanwhile, the relative change of the resistances on the two sides is larger during deformation, namely, the voltage change of a test end is larger, or the current change in an external circuit connected with the test end is larger, and the detection sensitivity is higher. The areas of the adjacent ultra-shallow doped regions 12 may be equal or different, and when the areas are equal, the resistances are equal (the species and concentration of the doped ions are the same), that is, when the wheatstone bridge is deformed, the wheatstone bridge is changed from balance to unbalance; when the areas are not equal, the resistances are not equal (the types and the concentrations of the doped ions are the same), namely, when the area is deformed, the Wheatstone bridge is changed from imbalance to imbalance. More preferably, the two ultra-shallow doped regions 12 corresponding to the long side are longer and shorter than the two ultra-shallow doped regions 12 corresponding to the short side, so that the relative change of the resistances of the two sides is larger when the silicon membrane is deformed, and thus the detection sensitivity is higher. The four ultra-shallow doped regions 12 are four resistors, and are connected by the metal leads 2 to form a Wheatstone bridge for detecting the change of the resistors, and the Wheatstone bridge can sensitively detect the change of the resistors. Specifically, when in use, of four end points of the metal lead 2 (i.e., four corners of the metal lead shown in fig. 5, or a metal lead having a larger area may be further disposed at the four corners to form a pin, so as to conveniently connect the power supply terminal and the test terminal), any two opposite end points are power supply terminals for connecting a power supply, and the other two opposite end points are test terminals for connecting an external test circuit, where the external test circuit may test a voltage between the two test terminals or may form a current in a loop test external test circuit, and both of the two may reflect a resistance change of the ultra-shallow doping region 12. Specifically, the relative change of the resistances of the two pairs of side ultra-shallow doped regions 12 is reflected, when the resistances of the four ultra-shallow doped regions 12 are equal, the wheatstone bridge is balanced, the voltage of the test end is zero, and when the strain occurs, the resistances of the side ultra-shallow doped regions 12 are unequal, namely, the wheatstone bridge starts to be unbalanced, and the voltage of the test end is not zero; more specifically, the relative change of the resistances of the two pairs of ultra-shallow doped regions 12 is larger, that is, the resistance difference between the two pairs of ultra-shallow doped regions 12 becomes larger, the more unbalanced the wheatstone bridge is, the larger the voltage at the test end is, and the higher the sensitivity is.

Furthermore, a groove is arranged on the outer side of the long side of the silicon membrane, the length of the groove is longer than that of the two side areas 12 with the corresponding side being ultra-shallow doped and longer, and the depth of the groove is more than 30nm; therefore, stress transfer in two directions of the silicon diaphragm is different, so that the resistance change of the ultra-shallow doped regions 12 corresponding to the long edges of the silicon diaphragm is larger, namely the resistance change of the ultra-shallow doped regions 12 on two sides is larger, the difference of the resistance change is larger, the Wheatstone bridge is unbalanced, the voltage of a test end is larger, the change is more obvious, and the detection sensitivity is higher.

Furthermore, above-mentioned pressure sensor is gauge pressure type sensor, the utility model discloses still disclose an absolute pressure type sensor. Specifically, glass is further fixedly arranged on one side of the concave structure 11 away from the ultra-shallow doped region 12, and a cavity is formed between the glass and the concave structure 11. The glass and the silicon substrate layer are fixedly connected by bonding at one side of the concave structure 11, specifically, the glass and the silicon wafer are bonded together by adopting an anodic bonding technology to form a vacuum cavity, and the vacuum degree in the vacuum cavity is higher than 5 multiplied by 10 ^-6 bar, the higher the vacuum, the higher the accuracy of the sensing. More specifically, the specific magnitude of the degree of vacuum is related to the bonding process as follows: and flattening the surfaces of the silicon-based layer to be bonded and the glass, and cleaning to ensure the close contact between the silicon-based layer and the glass. A silicon base layer to be bonded and glass are sandwiched between two electrodes, a negative electrode (cathode) is in contact with the glass, a positive electrode (anode) is in contact with the silicon base layer, a voltage of several hundred to several kilovolts is applied, heating is carried out to 752-932 ℃, positively charged sodium ions in the glass become mobile and move toward the cathode, a small amount of positive charge is left near the boundary in contact with the silicon base layer, and then they are fixed by electrostatic attraction. Negatively charged oxygen from the ions of the glass migrates toward the anode and reacts with silicon when reaching the boundary to form silicon dioxide; the chemical bond generated seals the silicon substrate and the glass together to form a vacuumA cavity. Therefore, a constant pressure is formed on one side, close to the glass, of the silicon diaphragm, when the pressure applied to one side, far away from the glass, of the silicon diaphragm changes, the silicon diaphragm deforms, so that the ultra-shallow doped region 12 on the silicon diaphragm deforms, and due to the piezoresistive effect, the resistance change of the ultra-shallow doped region obtains the change of the pressure to be measured by detecting the change of the resistance. Both sides of the gauge pressure type sensor are exposed in an environment to be detected, and only one side, far away from the concave structure 11, of the silicon diaphragm of the absolute pressure type sensor is exposed in the environment to be detected, so that the gauge pressure type sensor is suitable for detecting pressure change caused by pressure difference between the two sides, and the absolute pressure type sensor is suitable for detecting pressure in a closed environment.

During the application, will the utility model discloses pressure sensor fixes in the pressure environment that awaits measuring for pressure is used in on the silicon diaphragm, and under the pressure effect that awaits measuring, deformation takes place for the silicon diaphragm, and the deformation of silicon diaphragm makes the super shallow doping district 12 deformation on it, and its thickness changes, and according to the piezoresistive effect, the resistance in super shallow doping district 12 changes, surveys the resistance that obtains super shallow doping district 12 resistance through electric circuit and changes, obtains the change situation of pressure through surveying the resistance change, realizes the sensing. The utility model discloses pressure sensor can be used to survey any type of pressure, like atmospheric pressure, water pressure etc.. The doping depth of the ultra-shallow doping region 12 in the utility model is of nanometer order of magnitude, and when the thickness of the ultra-shallow doping region 12 changes, the thickness t before the change ₁ Is smaller, so that

Is larger, so that the change of the resistance Δ R of the ultra-shallow doped region 12 is larger, i.e. the same stress change makes the change of the resistance of the ultra-shallow doped region 12 larger, i.e. the sensitivity of the pressure sensing at the micro level is higher.

In addition, the utility model discloses still more sensitive change of surveying resistance based on wheatstone bridge; specifically, the deformation makes the variation difference of the resistance of the ultra-shallow doped regions 12 on the two pairs of sides large, the voltage of the test end is larger, and the sensitivity is improved. By enhancing the anisotropy of the stress transfer of the silicon membrane, the variation difference of the resistance of the two pairs of ultra-shallow doped regions 12 is larger, so that the detection sensitivity is enhanced. Specifically, the utility model discloses in through setting up concrete shape, the position of super shallow impurity district 12 of mixing to and add the recess, progressively promote the anisotropy of stress transmission to promote the change difference of the resistance of two offsides super shallow impurity district 12 of mixing, finally make sensor sensitivity promote.

The utility model discloses pressure sensor can detect the change of range thousandth, and for example, the range is 100kpa, can distinguish 0.1kpa at least. The utility model discloses pressure sensor can not only be used for the sensing of small pressure, can be used to any pressure range of range within range, specifically, the range depends on integrated quantity etc. the utility model has the advantages of sensing sensitivity is higher under small pressure.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. The utility model provides a piezoresistive pressure sensor, its characterized in that, pressure sensor includes silicon substrate, metal lead wire, a side of silicon substrate is provided with sunk structure, sunk structure's bottom forms the silicon diaphragm, the silicon diaphragm is kept away from the sunk structure one side be provided with the ultra-shallow district that mixes on the surface, the metal lead wire fixed set up in the silicon substrate is kept away from sunk structure one side, the ultra-shallow district that mixes passes through the metal lead wire is connected and is formed the electric circuit.

2. The piezoresistive pressure sensor according to claim 1, wherein the doping depth of said ultra-shallow doped region is in the order of nanometers.

3. The piezoresistive pressure sensor according to claim 2, wherein the doping ions of said ultra-shallow doped region are boron ions or phosphorous ions.

4. The piezoresistive pressure sensor according to claim 3, wherein there are four said ultra-shallow doped regions, and said four ultra-shallow doped regions are connected by metal wires to form a Wheatstone bridge.

5. The piezoresistive pressure sensor according to claim 4, wherein the doping thicknesses of the two ultra-shallow doped regions on opposite sides of the Wheatstone bridge are the same, and the doping thicknesses of the two ultra-shallow doped regions on adjacent sides are different.

6. The piezoresistive pressure sensor according to any of claims 1-5, wherein a glass is fixedly arranged on the side of said recessed structure away from said ultra-shallow doped region, and a cavity is formed between said glass and said recessed structure.

7. The piezoresistive pressure sensor according to claim 6, wherein said glass and said recessed structure are bonded and fixedly connected by anodic bonding technique.

8. The piezoresistive pressure sensor according to claim 1, wherein said metal lead wire is made using magnetron sputtering or deposition.

9. The piezoresistive pressure sensor according to claim 1, wherein said ultra-shallow doped region is fabricated using a low energy ion implantation process.

10. The piezoresistive pressure sensor according to claim 1, wherein the recessed structure is made using a time division multiplexing etching technique.

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