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CN116222838B - Sensing element and pressure sensor - Google Patents

Sensing element and pressure sensor Download PDF

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Publication number
CN116222838B
CN116222838B CN202310514446.5A CN202310514446A CN116222838B CN 116222838 B CN116222838 B CN 116222838B CN 202310514446 A CN202310514446 A CN 202310514446A CN 116222838 B CN116222838 B CN 116222838B
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substrate
layer
region
sensing element
piezoresistor
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CN116222838A (en
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温赛赛
邢昆山
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Suzhou Eboda Microsystem Technology Co.,Ltd.
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Suzhou Yiboda Optoelectronic Technology Co ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
    • B81C1/00349—Creating layers of material on a substrate
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
    • B81C1/00436—Shaping materials, i.e. techniques for structuring the substrate or the layers on the substrate
    • B81C1/00523—Etching material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y15/00—Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/18—Measuring force or stress, in general using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/26—Auxiliary measures taken, or devices used, in connection with the measurement of force, e.g. for preventing influence of transverse components of force, for preventing overload
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
    • G01L19/06—Means for preventing overload or deleterious influence of the measured medium on the measuring device or vice versa
    • G01L19/069—Protection against electromagnetic or electrostatic interferences
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
    • G01L9/02—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in ohmic resistance, e.g. of potentiometers, electric circuits therefor, e.g. bridges, amplifiers or signal conditioning
    • G01L9/06—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in ohmic resistance, e.g. of potentiometers, electric circuits therefor, e.g. bridges, amplifiers or signal conditioning of piezo-resistive devices

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Nanotechnology (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Health & Medical Sciences (AREA)
  • Molecular Biology (AREA)
  • General Health & Medical Sciences (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Electromagnetism (AREA)
  • Measuring Fluid Pressure (AREA)

Abstract

The invention relates to a sensing element and a pressure sensor, wherein the sensing element comprises a first substrate, a second substrate and a first sensor, wherein the second substrate is covered on the first substrate; at least one piezoresistor area is arranged in the second substrate, the piezoresistor area is close to the upper surface of the second substrate, the piezoresistor area is provided with a piezoresistor connecting area, and the piezoresistor connecting area is electrically contacted with a contact area; at least one protective layer covering the upper surface of the second substrate; at least one protection ring is arranged in the second substrate, and the piezoresistor area and the piezoresistor connecting area are positioned at the inner side of the protection ring; the shielding layer is arranged on the surface of the protective layer or between the protective layer and the piezoresistor area; wherein at least one of the first substrate, guard ring and shielding layer is connected to an external circuit through a contact region. The invention avoids the influence of free charges generated by the substrate on the piezoresistive region, and improves the precision and long-term stability of the pressure sensor.

Description

Sensing element and pressure sensor
Technical Field
The invention relates to the technical field of sensors, in particular to a sensing element and a pressure sensor.
Background
The pressure sensor is a sensor for converting pressure into an electric signal, is commonly called a pressure sensor in China, and can be classified into a piezoresistive type, a capacitive type, a resonant type, a piezoelectric type and the like according to a technical route. The piezoresistive pressure sensor has the advantages of high commercialization degree and wide application range because of the relative easiness and maturity of the manufacturing process, wide range coverage, low cost and the like.
The long-term stability of pressure sensors is of paramount importance in the industry, the military industry, etc. As a piezoresistive pressure sensor, the piezoresistive pressure sensor is more susceptible to the influence of external charges or an electric field, so that output drift, output floating and the like occur. Particularly, above the piezoresistive region, a certain charge accumulation is easily formed due to the influence of factors such as ion pollution, fixed charge, external charge, radiation and the like. For the sake of clarity of illustration, a simplified piezoresistive pressure sensor is shown in cross-section in fig. 1. When the upper protective layer 6 of the piezoresistive region 4 and the piezoresistive connection region 5 creates a positive charge accumulation, negative charge is attracted to the upper side to form a negative charge accumulation or inversion layer. At this time, the thickness of the piezoresistive region becomes thinner than that when no charge is accumulated, so that the resistance value of the piezoresistive region changes, and finally the output result is influenced to cause long-term stability drift. While the underside of the piezoresistive region, i.e., the substrate, also develops free charge for similar reasons, causing long-term stability problems.
Numerous scholars and companies have developed and contributed to numerous solutions to the above-mentioned problems. Academic p.l.p. Hoa et al, article "Influence of polycrystalline silicon as electrical shield on reliability and stability of piezoresistive sensors," originally placed polysilicon over the piezoresistive region, and reduced the effect of external charge on the piezoresistive by fixing the potential above. A large number of patents written by companies at home and abroad have similar solutions, such as CN110608819A, EP3832279A1, CN216410458U, US5231301A, US9790085B1. There are a scheme of using metal, n+ doping instead of polysilicon, and a scheme of surrounding a shielding ring around the piezoresistive region and the piezoresistive lead region at the same time.
However, the above-mentioned solutions do not solve the problem well that the free charge directly below the piezoresistive region affects the piezoresistive region. Some patents such as CN110608819a connect the substrate with a shield/high potential to "adsorb" the free charge of the substrate, but these connection points tend to be far from the piezoresistive region and because of the high resistance characteristics of the substrate, the high potential has insufficient free charge attraction capability under the piezoresistive region, and still some free charge can have an effect on the piezoresistive region, affecting the accuracy of the pressure sensor. Meanwhile, the external magnetic field can influence the charges of the substrate, the piezoresistive region and the piezoresistive connection region through the unshielded part of the bottom, so that the piezoresistive region is influenced, and the accuracy of the pressure sensor is also influenced.
Disclosure of Invention
Aiming at the defects of the prior art, the invention discloses a sensing element and a pressure sensor.
The technical scheme adopted by the invention is as follows:
a sensing element, comprising:
a first substrate having first and second surfaces opposite to each other in a thickness direction thereof;
a second substrate covering the first surface of the first substrate; having opposite first and second surfaces in a thickness direction of the second substrate, wherein the second surface of the second substrate is in contact with the first surface of the first substrate; at least one piezoresistor area is arranged in the second substrate, the piezoresistor area is close to the first surface of the second substrate, the piezoresistor area is provided with a piezoresistor connection area, and the piezoresistor connection area is electrically contacted with a contact area;
at least one protective layer covering the first surface of the second substrate;
the voltage dependent resistor area and the voltage dependent resistor connecting area are positioned on the inner side of the protection ring;
the shielding layer is arranged on the surface of the protective layer or between the protective layer and the piezoresistor area;
wherein at least one of the first substrate, the guard ring, and the shielding layer is connected to an external circuit through the contact region.
In some embodiments, the doping concentration of the second substrate is less than the doping concentration of the first substrate.
In some embodiments, the shielding layer is disposed on the surface of the protective layer, and the material of the shielding layer is one of a doped polysilicon layer, an aluminum layer, a silicon-chromium alloy layer, a platinum layer, a titanium layer and a nickel layer with doping substances.
In some embodiments, the shielding layer is disposed between the protective layer and the varistor region, the shielding layer being a doped layer with a dopant species.
In some embodiments, the dopant is one of boron, indium, arsenic, phosphorus, and antimony.
In some embodiments, the contact region has a conductive interconnect region for electrically biasing the varistor region through the contact region.
In some embodiments, the conductivity type of the first substrate is opposite to the conductivity type of the varistor region.
In some embodiments, the protective layer is a single layer, the protective layer is SiO 2 A layer.
In some embodiments, the protective layer is a multilayer, the protective layer comprising at least one layer of SiO 2 A layer and at least one SiN layer.
In some embodiments, the second surface of the first substrate is open to hollow regions.
A pressure sensor comprising a signal processing unit and at least one sensing element as described above, the signal processing unit converting a pressure signal of the sensing element into an output electrical signal.
In some embodiments, the sensing elements are plural, and the plural sensing elements are coupled by a sensor adjustment circuit.
Compared with the prior art, the technical scheme of the invention has the following advantages:
the sensing element is used for fixing the potential below the piezoresistor region through the first protective ring arranged between the piezoresistor region and the second surface of the substrate, and is in combined action with the second protective ring arranged between the protective layer and the first protective ring, and the potential is fixed on the shielding layer around the piezoresistor region, so that the influence of free charges generated by the outside and the substrate on the piezoresistor region is reduced.
Drawings
In order that the invention may be more readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings.
FIG. 1 is a cross-sectional view of a prior art simple sensing element.
FIG. 2 is a schematic diagram of a first embodiment of a sensing element according to the present invention.
FIG. 3 is a schematic diagram of a second embodiment of a sensing device according to the present invention.
FIG. 4 is a schematic diagram of a third embodiment of a sensing element in the present invention.
FIG. 5 is a schematic diagram of a fourth embodiment of a sensing element of the present invention.
FIG. 6 is a schematic diagram of a fifth embodiment of a sensing element of the present invention.
FIG. 7 is a schematic diagram of a sixth embodiment of a sensing element in the present invention.
FIG. 8 is a schematic diagram of a seventh embodiment of a sensing element in the present invention.
FIG. 9 is a schematic diagram of an embodiment eight of a sensing element in the present invention.
FIG. 10 is a schematic diagram of a sensing element of the present invention in accordance with a ninth embodiment.
FIG. 11 is a schematic diagram of an embodiment of a sensing element of the present invention.
FIG. 12 is a schematic diagram of an eleventh embodiment of a sensing element in the present invention.
FIG. 13 is a schematic diagram of a twelfth embodiment of a sensing element in the present invention.
FIG. 14 is a schematic diagram of a thirteenth embodiment of a sensing element in the present invention.
FIG. 15 is a schematic diagram of a fourteenth embodiment of a sensing element in the present invention.
FIG. 16 is a schematic diagram of an embodiment fifteen of a sensing element in the present invention.
FIG. 17 is a graph showing the resistance change of the piezoresistive region of the sensing element of the present invention with a non-shielding layer and a sensing element with a shielding layer and a second guard ring under different external electric fields.
Description of the specification reference numerals: 1. a first substrate; 2. a second substrate; 3. a protective ring; 4. a varistor region; 5. a varistor connection region; 6. a first protective layer; 7. a second protective layer; 8. a conductive interconnect region; 801. a contact region; 9. a shielding layer; 10. hollow areas.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and specific examples, which are not intended to be limiting, so that those skilled in the art will better understand the invention and practice it.
The foregoing and other features, aspects and advantages of the present invention will become more apparent from the following detailed description of the embodiments, read in conjunction with the accompanying drawings. The directional terms mentioned in the following embodiments are, for example: upper, lower, left, right, front or rear, etc., are merely references to the directions of the drawings. Thus, directional terminology is used for the purpose of illustration and is not intended to be limiting of the invention, and furthermore, like reference numerals refer to like elements throughout the embodiments.
Example 1:
as shown in fig. 2, a sensing element includes:
a first substrate 1 having opposite first and second surfaces in a thickness direction thereof;
a second substrate 2 covering the first surface of the first substrate 1; having opposite first and second surfaces in the thickness direction of the second substrate 2, wherein the second surface of the second substrate 2 is in contact with the first surface of the first substrate 1; at least one piezoresistor region 4 is arranged in the second substrate 2, the piezoresistor region 4 is close to the first surface of the second substrate 2, the piezoresistor region 4 is provided with a piezoresistor connection region 5, and the piezoresistor connection region 5 is electrically contacted with at least two contact regions 801;
at least one protective layer covering the first surface of the second substrate 2;
at least one guard ring 3 disposed in the second substrate 2, and the varistor region 4 and the varistor connecting region 5 are located inside the guard ring 3;
a shielding layer 9 disposed on the surface of the protective layer or between the protective layer and the varistor region 4;
wherein at least one of the first substrate 1, guard ring 3 and shielding layer 9 is connected to an external circuit through a contact region 801. It will be appreciated that the second substrate 2 and guard ring 3 and the shielding layer 9 form an enclosure for the varistor region 4 and the varistor-connection region 5.
In the present embodiment, the doping concentration of the second substrate 2 is smaller than that of the first substrate 1. Specifically, the doping concentration of the first substrate 1 is greater than 5×10 18 /cm 3 Therefore, the conductive material has high conductivity and can play a role of fixing potential; the doping concentration of the second substrate 2 is less than 1×10 19 /cm 3 It can be seen that the doping concentration of the second substrate 2 is smaller than the doping concentration of the first substrate 1.
In this embodiment, the manufacturing process of the second substrate 2 is as follows: first a layer of a low-doped second substrate 2 is grown on a first substrate 1, the doping concentration of the second substrate 2 is less than 1 x 10 19 /cm 3 。
In this embodiment, the material of the shielding layer 9 is a doped polysilicon layer with a doping substance. Specifically, the doping substance is one of boron, indium, arsenic, phosphorus and antimony.
In this embodiment, each contact region 801 has a conductive interconnect region 8, the conductive interconnect region 8 being used to electrically bias the varistor region 4 through the contact region 801.
In this embodiment, the conductivity type of the substrate 1 is opposite to the conductivity type of the varistor region 4. Specifically, the conductivity type of the substrate 1 may be p-type and the conductivity type of the varistor region 4 may be n-type, or the conductivity type of the substrate 1 may be n-type and the conductivity type of the varistor region 4 may be p-type.
In the present embodiment, the protective layers have two layers, which are respectively defined as a first protective layer 6 and a second protective layer 7 for convenience of description, wherein the first protective layer 6 is SiO 2 The layer, the second protective layer 7, is a SiN layer. It should be noted that the protective layer may be provided with only one SiO layer 2 The layer may be a protective layer having a certain insulation property.
In this embodiment, the second surface of the substrate 1 is provided with a hollow region 10, and the hollow region 10 may be formed by a groove or a notch provided on the second surface of the substrate 1.
Example 2:
as shown in fig. 3, the difference from embodiment 1 is that the first substrate 1 and the guard ring 3 are both connected to an external circuit through a contact region 801.
Example 3:
as shown in fig. 4, the difference from embodiment 1 is that the first substrate 1 is not connected to the guard ring 3 and the shielding layer 9, and is not connected to the external circuit through the contact region 801, in which case, since the second substrate 2 and the guard ring 3 and the shielding layer 9 form an enclosure for the varistor region 4 and the varistor connecting region 5, the enclosure can still have a certain absorption capacity for free charges, although the guard ring 3, the shielding layer 9 and the external circuit are not connected.
Example 4:
as shown in fig. 5, the difference from embodiment 1 is that the first substrate 1 is connected only to an external circuit through a contact region 801.
Example 5:
as shown in fig. 6, the difference from embodiment 1 is that the first substrate 1 and the shielding layer 9 are connected and connected to an external circuit through a contact region 801.
The manufacturing method of the sensing element of embodiment 1 to embodiment 5 is as follows:
s1, a layer of second substrate 2 is epitaxially grown on the first substrate 1, wherein the doping concentration of the first substrate 1 is more than 5 multiplied by 10 18 /cm 3 The doping concentration of the second substrate 2 is less than 1×10 19 /cm 3 。
S2, forming a piezoresistor region 4, a piezoresistor connecting region 5 and a protection ring 3 through multiple photoetching and injection or doping processes. The doping substance of the guard ring 3 may be one of boron, indium, arsenic, phosphorus and antimony, and the doping substance of the varistor region 4 is the same as the doping substance of the varistor connecting region 5, and the doping substance may be one of boron, indium, arsenic, phosphorus and antimony.
S3, forming a first protective layer 6 of 30-1500 nm, namely SiO, by using methods such as hot oxygen, LPCVD (low pressure vapor deposition) or PECVD (plasma enhanced vapor deposition) 2 A layer.
Forming a second protective layer 7 of SiN layer of 30nm-3000nm by LPCVD/PECVD, etc., wherein the protective layer can have only one SiO layer 2 Layers, and thus steps, are not necessary.
S4, forming a 100-1500 nm polycrystalline silicon layer by LPCVD or PECVD and the like, and removing the polycrystalline silicon layer by photoetching to form a shielding layer 9;
and S5, exposing the conductive interconnection area 8 through photoetching.
S6, photoetching and sputtering or evaporating a 100-1500 nm aluminum layer or a silicon-chromium alloy layer or a platinum layer or a titanium layer or a nickel layer or a doped polysilicon layer, and stripping to form a contact area 801, or sputtering or evaporating a 100-1500 nm aluminum layer or a silicon-chromium alloy layer or a platinum layer or a titanium layer or a nickel layer or a doped polysilicon layer, and removing by photoetching to form a contact area 801.
And S7, etching a window on the second surface of the first substrate 1 by photoetching and etching a hollow region 10 by etching or deep silicon etching.
Example 6:
as shown in fig. 7, the difference from embodiment 1 is that: a shielding layer 9 disposed between the protective layer and the varistor region 4; specifically, the shielding layer 9 is formed by photolithography and implantation or doping processes to form a doped layer different from the doped material in the varistor region 4, and thus the position of the shielding layer 9 is different from that of the shielding layer 9 in embodiments 1 to 5.
Wherein the first substrate 1, guard ring 3 and shielding layer 9 are connected and connected to an external circuit via contact areas 801.
Example 7:
as shown in fig. 8, the difference from embodiment 6 is that the first substrate 1 and the guard ring 3 are both connected to an external circuit through a contact region 801.
Example 8:
as shown in fig. 9, the difference from embodiment 6 is that the first substrate 1 is not connected to the guard ring 3 and the shielding layer 9, and is not connected to the external circuit through the contact region 801, in which case, since the second substrate 2 and the guard ring 3 and the shielding layer 9 form an enclosure for the varistor region 4 and the varistor connecting region 5, the enclosure can still have a certain absorption capacity for free charges, although the guard ring 3, the shielding layer 9 and the external circuit are not connected.
Example 9:
as shown in fig. 10, the difference from embodiment 6 is that the first substrate 1 is connected to only an external circuit through a contact region 801.
Example 10:
as shown in fig. 11, the difference from embodiment 6 is that the first substrate 1 and the shielding layer 9 are connected and connected to an external circuit through a contact region 801.
The manufacturing method of the sensing element of embodiment 6-embodiment 10 is as follows:
s1, a layer of second substrate 2 is epitaxially grown on the first substrate 1, wherein the doping concentration of the first substrate 1 is more than 5 multiplied by 10 18 /cm 3 The doping concentration of the second substrate 2 is less than 1×10 19 /cm 3 。
S2, forming a piezoresistor region 4, a piezoresistor connecting region 5 and a protection ring 3 through multiple photoetching and injection or doping processes. Wherein, the doping material of the protection ring 3 can be one of boron, indium, arsenic, phosphorus and antimony; the doping material of the varistor region 4 is the same as the doping material of the varistor connecting region 5 and may be one of boron, indium, arsenic, phosphorus and antimony.
S3, forming a doped layer, namely a shielding layer 9, which is different from the piezoresistive region through photoetching and implantation or doping processes, wherein the doping substance can be one of boron, indium, arsenic, phosphorus and antimony.
S4, forming a first protective layer 6 of 30-1500 nm, namely SiO, by using methods such as hot oxygen, LPCVD (low pressure vapor deposition) or PECVD (plasma enhanced vapor deposition) 2 And (3) a protective layer.
Forming a second protective layer 7 of SiN with a thickness of 30nm-3000nm by LPCVD/PECVD, etc., wherein the protective layer can be formed of only one SiO layer 2 A protective layer, and thus a step is not necessary.
And S5, exposing the conductive interconnection area 8 through photoetching.
S6, photoetching and sputtering or evaporating a 100-1500 nm aluminum layer or a silicon-chromium alloy layer or a platinum layer or a titanium layer or a nickel layer or a doped polysilicon layer, and stripping to form a contact area 801, or sputtering or evaporating a 100-1500 nm aluminum layer or a silicon-chromium alloy layer or a platinum layer or a titanium layer or a nickel layer or a doped polysilicon layer, and removing by photoetching to form a contact area 801.
And S7, etching a window on the second surface of the first substrate 1 by photoetching and etching a hollow region 10 by etching or deep silicon etching.
Example 11:
as shown in fig. 12, the difference from embodiment 1 is that the shielding layer 9 is an aluminum layer.
Wherein the first substrate 1, guard ring 3 and shielding layer 9 are connected simultaneously and via contact area 801 to an external circuit.
Example 12:
as shown in fig. 13, embodiment 11 is different in that the first substrate 1 and the guard ring 3 are connected, and are connected to an external circuit through a contact region 801.
Example 13:
as shown in fig. 14, the difference from embodiment 11 is that the first substrate 1 is not connected to the guard ring 3 and the shielding layer 9, and is not connected to the external circuit through the contact region 801, and in this case, since the second substrate 2 and the guard ring 3 and the shielding layer 9 form an enclosure for the varistor region 4 and the varistor connecting region 5, the enclosure can still have a certain absorption capacity for free charges although the guard ring 3, the shielding layer 9 and the external circuit are not connected.
Example 14:
as shown in fig. 15, the difference from embodiment 11 is that the first substrate 1 is connected only to an external circuit through a contact region 801.
Example 15:
as shown in fig. 16, the difference from embodiment 11 is that the first substrate 1 and the shielding layer 9 are connected and connected to an external circuit through a contact region 801.
The manufacturing method of the sensing element of embodiment 11-embodiment 15 is as follows:
s1, a layer of second substrate 2 is epitaxially grown on the first substrate 1, wherein the doping concentration of the first substrate 1 is more than 5 multiplied by 10 18 /cm 3 The doping concentration of the second substrate 2 is less than 1×10 19 /cm 3 。
S2, forming a piezoresistor region 4, a piezoresistor connecting region 5 and a protection ring 3 through multiple photoetching and injection or doping processes. Wherein, the doping material of the protection ring 3 can be one of boron, indium, arsenic, phosphorus and antimony; the doping material of the varistor region 4 is the same as the doping material of the varistor connecting region 5 and may be one of boron, indium, arsenic, phosphorus and antimony.
S3, forming a first protective layer 6 of 30-1500 nm, namely SiO, by using methods such as hot oxygen, LPCVD (low pressure vapor deposition) or PECVD (plasma enhanced vapor deposition) 2 And (3) a protective layer.
A second protective layer 7 of 30nm to 3000nm, i.e. SiN protective layer, is formed by means of LPCVD or PECVD or the like, which is not necessary since the protective layer may have only one SiO2 layer.
And S4, exposing the conductive interconnection area 8 through photoetching.
S5, photoetching and sputtering or evaporating a 100-1500 nm aluminum layer or a silicon-chromium alloy layer or a platinum layer or a titanium layer or a nickel layer or a doped polysilicon layer, and stripping to form a contact area 801 and a shielding layer 9, or sputtering or evaporating a 100-1500 nm aluminum layer or a silicon-chromium alloy layer or a platinum layer or a titanium layer or a nickel layer or a doped polysilicon layer, and removing by photoetching and etching to form the contact area 801 and the shielding layer 9.
S6, etching a window on the second surface of the substrate 1 by photoetching and etching a hollow region 10 by etching or deep silicon etching.
To sum up:
the difference between examples 1-5 is that: the first substrate 1 is connected to an external circuit.
The difference between examples 6-10 is that: the first substrate 1 is connected to an external circuit. Example 6-example 10 has the advantage over the other examples that the residual stress created in the film region above the hollow region 10 is less, and because the film region is relatively thin, the stress created by the pressure in the film is greater, and the sensitivity is correspondingly greater.
The difference between examples 11-15 is: the first substrate 1 is connected to an external circuit. In example 11-example 15, the shielding layer 9 and the contact region 801 are formed integrally, and the manufacturing method has fewer steps and lower cost compared with other examples.
In still other embodiments, a pressure sensor includes a signal processing unit and at least one sensing element as provided in any one of embodiments 1-15, the signal processing unit converting a pressure signal of the sensing element into an output electrical signal. Of course, there may be multiple sensing elements coupled by the sensor conditioning circuit.
Because uncertainty exists in the test process and the test cost is high at one time, the resistance values of the piezoresistive areas of the sensing element provided by the invention and the sensing element without the shielding layer, the sensing element with the shielding layer and the sensing element with the second protection ring under different external electric fields are compared through process simulation, and as shown in fig. 17, the resistance value change of the sensing element without the shielding layer is the largest; the sensing element with the shielding layer and the second protection ring, namely the prior art disclosed in the literature, is used for providing relatively gentle resistance change of the existing sensor, so that the influence of an electric field on the resistance value of the piezoresistor is effectively reduced due to the existence of the shielding layer; the resistance change rate of the sensing element provided by the invention is further reduced, which indicates that the influence of free charge on the resistance of the piezoresistor is further reduced.
In the description of the embodiments of the present invention, it should also be noted that, unless explicitly specified and limited otherwise, the terms "disposed," "connected," and "connected" should be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations and modifications of the present invention will be apparent to those of ordinary skill in the art in light of the foregoing description. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present invention.

Claims (10)

1. A sensing element, characterized by: comprising the following steps:
a first substrate (1) having first and second surfaces opposite to each other in a thickness direction thereof;
a second substrate (2) covering the first surface of the first substrate (1); having opposite first and second surfaces in a thickness direction of the second substrate (2), wherein the second surface of the second substrate (2) is in contact with the first surface of the first substrate (1); at least one piezoresistor area (4) is arranged in the second substrate (2), the piezoresistor area (4) is close to the first surface of the second substrate (2), the piezoresistor area (4) is provided with a piezoresistor connection area (5), and the piezoresistor connection area (5) is electrically contacted with a contact area (801);
at least one protective layer covering the first surface of the second substrate (2);
at least one protection ring (3) arranged in the second substrate (2), and the piezoresistor region (4) and the piezoresistor connecting region (5) are positioned inside the protection ring (3);
a shielding layer (9) arranged on the surface of the protective layer or between the protective layer and the varistor region (4); when the shielding layer (9) is arranged on the surface of the protective layer, the shielding layer (9) is made of one of a doped polysilicon layer, an aluminum layer, a silicon chromium alloy layer, a platinum layer, a titanium layer and a nickel layer which are provided with doping substances; when the shielding layer (9) is arranged between the protective layer and the varistor region (4), the shielding layer (9) is a doped layer with a doping substance;
wherein at least one of the first substrate (1), the guard ring (3) and the shielding layer (9) is connected to an external circuit via the contact region (801).
2. The sensing element of claim 1, wherein: the doping concentration of the second substrate (2) is smaller than the doping concentration of the first substrate (1).
3. The sensing element of any one of claim 1, wherein: the doping substance is one of boron, indium, arsenic, phosphorus and antimony.
4. The sensing element of claim 1, wherein: the contact region (801) has a conductive interconnect region (8), the conductive interconnect region (8) being used for electrically biasing the varistor region (4) via the contact region (801).
5. The sensing element of claim 1, wherein: the conductivity type of the first substrate (1) is opposite to the conductivity type of the varistor region (4).
6. The sensing element of claim 1, wherein: the protective layer is a single layer, and the protective layer is SiO 2 A layer.
7. The sensing element of claim 1, wherein: the protective layer is a plurality of layers and comprises at least one layer of SiO 2 A layer and at least one SiN layer.
8. The sensing element of claim 1, wherein: the second surface of the first substrate (1) is provided with a hollow area (10).
9. A pressure sensor, characterized by: comprising a signal processing unit and at least one sensing element according to any of claims 1-8, said signal processing unit converting a pressure signal of said sensing element into an output electrical signal.
10. The pressure sensor of claim 9, wherein: the sensing elements are plural and are coupled through a sensor adjustment circuit.
CN202310514446.5A 2023-05-09 2023-05-09 Sensing element and pressure sensor Active CN116222838B (en)

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