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CN117346836A - Multifunctional sensor and preparation method thereof - Google Patents

Multifunctional sensor and preparation method thereof Download PDF

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Publication number
CN117346836A
CN117346836A CN202311302581.XA CN202311302581A CN117346836A CN 117346836 A CN117346836 A CN 117346836A CN 202311302581 A CN202311302581 A CN 202311302581A CN 117346836 A CN117346836 A CN 117346836A
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CN
China
Prior art keywords
sensitive unit
humidity
electrode group
substrate
unit
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CN202311302581.XA
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Chinese (zh)
Inventor
李若朋
何凯
汪民
许玉方
钟文兵
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Guangzhou Dexin Semiconductor Technology Co ltd
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Guangzhou Dexin Semiconductor Technology Co ltd
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Priority to CN202311302581.XA priority Critical patent/CN117346836A/en
Publication of CN117346836A publication Critical patent/CN117346836A/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D21/00—Measuring or testing not otherwise provided for
    • G01D21/02—Measuring two or more variables by means not covered by a single other subclass
    • 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
    • B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
    • B81C1/00134—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems comprising flexible or deformable structures
    • B81C1/0015—Cantilevers
    • 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
    • B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
    • B81C1/00134—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems comprising flexible or deformable structures
    • B81C1/00158—Diaphragms, membranes
    • 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

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

Abstract

The invention provides a multifunctional sensor and a preparation method thereof, wherein the sensor comprises a substrate, a peripheral circuit, a temperature-sensitive unit, a humidity-sensitive unit, a pressure-sensitive unit and a heating unit; the temperature-sensitive unit is arranged on the substrate and is electrically connected with the peripheral circuit through a first electrode group connected with the temperature-sensitive unit; the humidity-sensitive unit is arranged on the substrate and is electrically connected with the peripheral circuit through a second electrode group connected with the humidity-sensitive unit; the heating unit surrounds the humidity-sensitive unit and is arranged on the substrate, and is electrically connected with the peripheral circuit through a third electrode group connected with the heating unit; the pressure-sensitive unit surrounds the heating unit and is arranged on the substrate, and is electrically connected with the peripheral circuit through a fourth electrode group connected with the pressure-sensitive unit. The multifunctional sensor provided by the invention has the advantages that the humidity-sensitive unit can rapidly remove the condensed water under the low-temperature high-humidity condition, so that the normal operation of the sensor is ensured, and the response speed of the sensor is improved.

Description

Multifunctional sensor and preparation method thereof
Technical Field
The invention relates to the technical field of sensor preparation, in particular to a multifunctional sensor and a preparation method thereof.
Background
A sensor is a device or means that senses a defined measured signal and converts it into a usable signal according to a certain law, and is usually composed of a sensor element and a conversion element. MEMS (Micro-Electro-Mechanical Systems) technology is a Micro-electromechanical system technology, which combines various subjects such as Micro-electromechanical technology, semiconductor technology, micro-nano processing technology and material science, and has the main characteristics of small size, high integration and high precision, and can be used in the fields of environmental monitoring, automobiles, medical treatment and the like. The combination of MEMS technology and sensor technology will greatly promote the development of sensors, bringing more convenience to people's life.
The development of MEMS technology advances the development of miniaturization and integration of sensors, such as BME688 products introduced by Bosch company, and temperature, humidity and pressure detection units are integrated on one sensor chip, so that the temperature, humidity and pressure measurement functions can be realized. However, under the severe working conditions of low temperature and high humidity, condensation water is easy to generate on the surface of a sensitive layer of the humidity sensor, normal operation and response speed of the sensor are affected, and long-term drift of the sensor is problematic.
Disclosure of Invention
The invention aims to provide a multifunctional sensor and a preparation method thereof, which are used for solving the technical problems, and the humidity-sensitive unit of the multifunctional sensor can rapidly remove condensed water under the conditions of low temperature and high humidity, so that the normal operation of the sensor is ensured, and the response speed of the sensor is improved.
In addition, the humidity sensitive unit can be replaced by a gas sensitive unit according to different requirements, namely the humidity sensitive material of the humidity sensitive unit is replaced by a gas sensitive material, and the gas sensor can be manufactured.
The invention provides a multifunctional sensor, which comprises a substrate and a peripheral circuit; the device also comprises a temperature-sensitive unit, a humidity-sensitive unit, a pressure-sensitive unit and a heating unit; wherein:
the temperature-sensitive unit is arranged on the substrate and is electrically connected with the peripheral circuit through a first electrode group connected with the temperature-sensitive unit;
the humidity-sensitive unit is arranged on the substrate and is electrically connected with the peripheral circuit through a second electrode group connected with the humidity-sensitive unit;
the heating unit surrounds the humidity-sensitive unit and is arranged on the substrate, and is electrically connected with the peripheral circuit through a third electrode group connected with the heating unit;
the pressure-sensitive unit surrounds the heating unit and is arranged on the substrate, and is electrically connected with the peripheral circuit through a fourth electrode group connected with the pressure-sensitive unit.
In the scheme, for the humidity-sensitive material, the heating unit is arranged around the humidity-sensitive unit in a surrounding manner, and the heating unit can be used for heating under the condition of low temperature and high humidity, so that the condensed water of the sensor is rapidly removed, the normal operation of the sensor is ensured, the response speed is improved, and the influence of dew condensation and organic pollution on the humidity-sensitive material is reduced. In addition, the gas-sensitive unit can be prepared according to different requirements, for example, the humidity-sensitive material is replaced by the gas-sensitive material, and the gas-sensitive sensor can be prepared.
Further, the pressure-sensitive unit comprises a plurality of segments of piezoresistive strips and a plurality of interconnecting structures; wherein:
the fourth electrode group is arranged on the piezoresistive strip and connected with the piezoresistive strip;
the piezoresistive strips are sequentially arranged, encircle the periphery of the heating unit and are arranged on the substrate, and the two sections of piezoresistive strips are connected through the interconnection structure;
the interconnection structure connects the piezoresistive strips and forms a Wheatstone bridge with the fourth electrode group.
Further, a sensing suspension film is arranged on one side of the piezoresistive strip away from the heating unit, and the piezoresistive strip is arranged on the edge of the sensing suspension film so as to subject the piezoresistive strip to maximum stress.
In the scheme, the pressure applied by the outside can be fed back to the piezoresistive strip by the arrangement of the sensing suspended membrane, so that the pressure value of the outside can be sensitively measured; on the other hand, due to poor heat conductivity of the sensing suspended film, the heating efficiency of the heating units around the humidity-sensitive unit can be improved, and the power consumption of the sensor can be reduced.
Further, a humidity sensing film layer prepared from a humidity sensing material is arranged on the humidity sensing unit; correspondingly, a gas sensitive material is arranged on the gas sensitive unit.
In the scheme, the humidity sensing film layer is used for sensing the moisture condition of the surrounding environment and enabling the humidity sensitive unit to generate corresponding signals so as to accurately monitor the humidity condition of the surrounding environment; the gas sensitive material is used for sensing the gas condition of the environment and enabling the gas sensitive unit to generate corresponding signals so as to accurately monitor the gas condition of the surrounding environment.
Further, the humidity-sensitive unit is disposed above the pressure-sensitive unit suspension film.
In the scheme, the humidity-sensitive unit is positioned above the pressure-sensitive unit in the whole sensor three-dimensional device and is arranged on the sensing suspension film of the pressure-sensitive unit, so that the size of the multifunctional sensor can be effectively reduced, the production cost is reduced, and the production process difficulty is also reduced.
The multifunctional sensor provided by the scheme integrates the temperature sensitive unit, the humidity sensitive unit and the pressure sensitive unit on one sensor chip, so that the comprehensive performance of the sensor can be effectively improved. The high-precision temperature-sensitive unit can more accurately perform temperature compensation on the pressure-sensitive unit and the humidity-sensitive unit; and secondly, the humidity-sensitive unit is prepared on the sensing suspension film of the pressure-sensitive unit, so that the characteristic of poor heat conduction of the sensing suspension film of the pressure-sensitive unit can be fully utilized, the humidity-sensitive unit can be heated under lower power, and the heating efficiency is improved. The temperature sensitive unit, the humidity sensitive unit and the pressure sensitive unit can be mutually influenced, meanwhile, the process difficulty can be reduced, and the reliability of the sensor is improved.
The invention also provides a preparation method of the multifunctional sensor, which comprises the following steps:
preparing a pressure-sensitive unit and a fourth electrode group on the determined substrate to obtain a first substrate;
plating a Ti-Pt metal film on the first substrate to prepare a temperature sensitive unit, a first electrode group, a second electrode group, a heating unit and a third electrode group, and preparing a humidity sensitive unit to obtain a second substrate; the heating unit is arranged around the humidity-sensitive unit;
and preparing a peripheral circuit electrically connected with the fourth electrode group, the first electrode group, the second electrode group and the third electrode group based on the second substrate so as to complete the preparation of the multifunctional sensor.
The multifunctional sensor prepared by the scheme is characterized in that the heating unit is arranged around the humidity-sensitive unit for the humidity-sensitive material, and the humidity-sensitive material can be heated by the heating unit under the low-temperature high-humidity condition, so that the condensed water of the sensor is rapidly removed, the normal operation of the sensor is ensured, and the response speed is improved. In addition, the gas-sensitive unit can be prepared according to different requirements, for example, the humidity-sensitive material is replaced by the gas-sensitive material, and the gas-sensitive sensor can be prepared. And the temperature-sensitive unit, the first electrode group, the second electrode group, the heating unit and the third electrode group can be directly prepared from the Ti-Pt metal film through photoetching and etching processes, and the temperature-sensitive unit, the first electrode group, the second electrode group, the heating unit and the third electrode group are simple in process and convenient and quick to operate. Wherein: the second electrode group is an interdigital electrode of the humidity-sensitive unit.
Further, the preparing the pressure sensitive unit and the fourth electrode group on the determined substrate, and obtaining the first substrate specifically includes:
growing a silicon oxide film on the determined substrate;
arranging a plurality of sections of piezoresistive strips and a plurality of interconnection structures on the surface of a substrate on which a silicon oxide film grows by adopting an ion implanter;
the piezoresistive strips are sequentially arranged, encircle the periphery of the heating unit and are arranged on the substrate, and the two sections of piezoresistive strips are connected through the interconnection structure;
a fourth electrode group connected with the piezoresistive strip is arranged; the interconnection structure connects the piezoresistive strips and forms a Wheatstone bridge with the fourth electrode group.
Further, after obtaining the second substrate, the method further includes: and preparing a back cavity on one side of the second substrate far away from the heating unit by adopting a dry etching method or a wet etching method, and preparing a sensing suspension film in the back cavity, wherein the piezoresistive strips are arranged at the edge of the sensing suspension film.
In the scheme, the piezoresistive strip is arranged at the edge of the sensing suspension film so as to subject the piezoresistive strip to the maximum stress. The arrangement of the sensing suspension film can feed back the external applied pressure to the piezoresistive strip on one hand, so that the external pressure value can be sensitively measured; on the other hand, due to poor heat conductivity of the sensing suspended film, the heating efficiency of the heating units around the humidity-sensitive unit can be improved, and the power consumption of the sensor can be reduced.
Further, the preparing of the humidity sensitive unit comprises: and arranging a humidity sensing film layer prepared from a humidity sensitive material on the second electrode group so as to finish the preparation of the humidity sensitive unit. Correspondingly, if the electrode is a gas-sensitive unit, a corresponding gas-sensitive material is arranged on the second electrode group.
Further, the humidity-sensitive unit is disposed above the pressure-sensitive unit suspension film.
The multifunctional sensor prepared by the scheme integrates the temperature sensitive unit, the humidity sensitive unit/the gas sensitive unit and the pressure sensitive unit on one sensor chip, so that the comprehensive performance of the sensor can be effectively improved. The high-precision temperature-sensitive unit can accurately measure temperature, and the measured temperature parameters can be used for realizing temperature compensation of the pressure-sensitive unit and the humidity-sensitive unit/gas-sensitive unit; secondly, the humidity-sensitive unit/gas-sensitive unit can be prepared on the cavity of the pressure-sensitive unit, so that the chip size can be reduced, and the cost can be reduced; in addition, the characteristics of poor heat conduction of the sensing suspended film of the pressure-sensitive unit are fully utilized by the humidity-sensitive unit/gas-sensitive unit, and the humidity-sensitive unit/gas-sensitive unit can be heated under lower power, so that the heating efficiency is improved. The temperature-sensitive unit, the humidity-sensitive unit/the gas-sensitive unit and the pressure-sensitive unit can be mutually influenced by different sensors, meanwhile, the process difficulty can be reduced, and the reliability of the sensors is improved.
In addition, by changing the components of the humidity/gas sensitive material, different humidity/gas sensitive sensors can be prepared, and the application range of the sensor is widened.
Drawings
FIG. 1 is a schematic diagram of a multifunctional sensor according to an embodiment of the present invention;
FIG. 2 is a schematic flow chart of a method for manufacturing a multifunctional sensor according to an embodiment of the present invention;
FIG. 3 is a flowchart of a method for preparing a multifunctional sensor according to an embodiment of the present invention;
FIG. 4 is a second flowchart of a preparation of a multifunctional sensor according to an embodiment of the present invention;
FIG. 5 is a third flowchart of a preparation of a multifunctional sensor according to an embodiment of the present invention;
FIG. 6 is a flowchart of a preparation process of a multifunctional sensor according to an embodiment of the present invention;
FIG. 7 is a flowchart fifth exemplary embodiment of a method for preparing a multifunctional sensor;
FIG. 8 is a flowchart sixth of a preparation process of a multifunctional sensor according to an embodiment of the present invention;
FIG. 9 is a flowchart seventh of a preparation method of a multifunctional sensor according to an embodiment of the present invention;
FIG. 10 is a flowchart eight of a multi-functional sensor manufacturing process according to an embodiment of the present invention;
wherein: 1. a substrate; 2. silicon oxide; 3. a piezoresistive strip; 4. an interconnect structure; 5. aluminum; 6. silicon oxide/silicon nitride; 7. a Ti-Pt layer; 8. a moisture sensitive film layer; 9. a back cavity; 10. a temperature-sensitive unit; 11. a moisture sensitive unit; 12. a pressure sensitive unit; 13. a heating unit; 14. a peripheral circuit; 15. a first electrode group; 16. a second electrode group; 17. a third electrode group; 18. and a fourth electrode group.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1, the present embodiment provides a multifunctional sensor including a substrate 1 and a peripheral circuit 14; the temperature-sensitive unit 10, the humidity-sensitive unit 11, the pressure-sensitive unit 12 and the heating unit 13 are also included; wherein:
the temperature-sensitive unit 10 is disposed on the substrate 1, and is electrically connected to the peripheral circuit 14 through a first electrode group 15 connected to the temperature-sensitive unit 10;
the humidity sensitive unit 11 is arranged on the substrate 1 and is electrically connected with the peripheral circuit 14 through a second electrode group 16 connected with the humidity sensitive unit 11;
the heating unit 13 surrounds the humidity-sensitive unit 11 and is arranged on the substrate 1, and is electrically connected with the peripheral circuit 14 through a third electrode group 17 connected with the heating unit 13;
the pressure-sensitive unit 12 surrounds the heating unit 13 and is arranged on the substrate 1, which is electrically connected to the peripheral circuit 14 via a fourth electrode group 18 connected to the pressure-sensitive unit 12.
In this embodiment, the heating unit 13 is disposed around the humidity-sensitive unit 11, and for the humidity-sensitive unit, the heating unit 13 can heat the humidity-sensitive unit under the conditions of low temperature and high humidity, so as to quickly remove the condensation water of the sensor, ensure the normal operation of the sensor, improve the response speed, and reduce the influence of condensation and organic pollution on the humidity-sensitive material. In addition, the gas-sensitive unit can be prepared according to different requirements, for example, the humidity-sensitive material is replaced by the gas-sensitive material, and the gas-sensitive sensor can be prepared.
Further, the pressure sensitive unit 12 comprises several segments of piezoresistive strips 3 and several interconnecting structures 4; wherein:
the fourth electrode group 18 is arranged on the piezoresistive strip 3 and connected with the piezoresistive strip 3;
the piezoresistive strips 3 are sequentially arranged, surround the periphery of the heating unit 13 and are arranged on the substrate 1, and two sections of piezoresistive strips 3 are connected through the interconnection structure 4;
the interconnect structure 4 connects the segments of the piezoresistive strip 3 and forms a wheatstone bridge with the fourth electrode set 18.
Further, a sensing suspension membrane is arranged on the side of the piezoresistive strip 3 remote from the heating unit 13, and the piezoresistive strip is arranged at the edge of the sensing suspension membrane so as to subject the piezoresistive strip to maximum stress.
In this embodiment, the arrangement of the sensing suspension film can feedback the external pressure to the piezoresistive strip 3 on one hand, so as to sensitively measure the external pressure value; on the other hand, due to poor thermal conductivity of the sensing suspended film, the heating efficiency of the heating unit 13 around the humidity-sensitive unit 11 can be improved, and the power consumption of the sensor can be reduced.
Further, a humidity sensing film layer 8 made of a humidity sensitive material is provided on the humidity sensitive unit 11; correspondingly, a gas sensitive material is arranged on the gas sensitive unit.
In this embodiment, the humidity sensing film layer 8 is used for sensing the moisture condition of the surrounding environment, and making the humidity sensing unit 11 generate a corresponding signal to accurately monitor the humidity condition of the surrounding environment; the gas sensitive material is used for sensing the gas condition of the surrounding environment and enabling the gas sensitive unit to generate corresponding signals so as to accurately monitor the gas condition.
Further, the humidity sensitive unit 11 is disposed above the pressure sensitive unit 12.
In the embodiment, the humidity-sensitive unit 11 is located above the pressure-sensitive unit 12 in the whole sensor three-dimensional device and is arranged on the sensing suspension film of the pressure-sensitive unit 12, so that the size of the multifunctional sensor can be effectively reduced, the production cost is reduced, and the difficulty of the production process is also reduced.
The multifunctional sensor provided by the embodiment integrates the temperature-sensitive unit 10, the humidity-sensitive unit 11 and the pressure-sensitive unit 12 on one sensor chip, so that the comprehensive performance of the sensor can be effectively improved. The high-precision temperature-sensitive unit 10 can more accurately perform temperature compensation on the pressure-sensitive unit 12 and the humidity-sensitive unit 11; secondly, the humidity-sensitive unit 11 is prepared on the sensing suspension film of the pressure-sensitive unit 12, so that the characteristic of poor heat conduction of the sensing suspension film of the pressure-sensitive unit 12 can be fully utilized, the humidity-sensitive unit 11 can be heated under lower power, and the heating efficiency is improved. The temperature-sensitive unit 10, the humidity-sensitive unit 11 and the pressure-sensitive unit 12 can be mutually influenced, meanwhile, the process difficulty can be reduced, and the reliability of the sensor can be improved.
Referring to fig. 2, the embodiment further provides a method for manufacturing the multifunctional sensor, which includes the following steps:
s1: preparing a pressure-sensitive unit 12 and a fourth electrode group 18 on the determined substrate 1 to obtain a first substrate;
s2: plating a Ti-Pt metal film on the first substrate to prepare a temperature sensitive unit 10, a first electrode group 15, a second electrode group 16, a heating unit 13 and a third electrode group 17, and preparing a humidity sensitive unit 11 to obtain a second substrate; the heating unit 13 is arranged around the humidity sensitive unit 11;
s3: based on the second substrate, the peripheral circuit 14 electrically connected to the fourth electrode group 18, the first electrode group 15, the second electrode group 16 and the third electrode group 17 is prepared to complete the preparation of the multifunctional sensor.
For the multifunctional sensor prepared by the embodiment, the heating unit 13 is arranged around the humidity-sensitive unit 11 for the humidity-sensitive material, and the heating unit 13 can be used for heating under the low-temperature and high-humidity conditions, so that the condensation water of the sensor is rapidly removed, the normal operation of the sensor is ensured, and the response speed is improved. In addition, the gas-sensitive unit can be prepared according to different requirements, for example, the humidity-sensitive material is replaced by the gas-sensitive material, and the gas-sensitive sensor can be prepared. And the temperature-sensitive unit 10, the first electrode group 15, the second electrode group 16, the heating unit 14 and the third electrode group 17 can be directly prepared from the Ti-Pt metal film through photoetching technology, and the technology is simple, and the operation is convenient and quick. Wherein: the second electrode group is an interdigital electrode of the humidity-sensitive unit.
Further, the preparation of the pressure-sensitive unit 12 and the fourth electrode set 18 on the determined substrate 1 obtains a first substrate, specifically:
growing a silicon oxide 2 film on the determined substrate 1;
the method comprises the steps that an ion implanter is adopted to set a plurality of sections of piezoresistive strips 3 and a plurality of interconnection structures 4 on the surface of a substrate 1 for growing a silicon oxide 2 film;
the piezoresistive strips 3 are sequentially arranged, surround the periphery of the heating unit 13 and are arranged on the substrate 1, and two sections of piezoresistive strips 3 are connected through the interconnection structure 4;
a fourth electrode group 18 connected to the piezoresistive strip 3 is provided; the interconnect structure 4 connects the segments of the piezoresistive strip 3 and forms a wheatstone bridge with the fourth electrode set 18.
Further, after obtaining the second substrate, the method further includes: and preparing a back cavity 9 on one side of the second substrate far away from the heating unit 13 by adopting a dry etching method or a wet etching method, and preparing a sensing suspension film in the back cavity 9, wherein the piezoresistive strip 3 is arranged at the edge of the sensing suspension film.
In this embodiment, the piezoresistive strip 3 is positioned at the edge of the sensing diaphragm so that the piezoresistive strip 3 is subjected to the greatest stress. The arrangement of the sensing suspension film can feed back the external applied pressure to the piezoresistive strip 3 on one hand, so that the external pressure value can be sensitively measured; on the other hand, due to poor thermal conductivity of the sensing suspended film, the heating efficiency of the heating unit 13 around the humidity-sensitive unit 11 can be improved, and the power consumption of the sensor can be reduced.
Further, the preparing of the humidity sensitive unit 11 includes: a humidity sensitive membrane layer 8 made of a humidity sensitive material is provided on the second electrode group 16 to complete the preparation of the humidity sensitive unit. Correspondingly, if the electrode is a gas-sensitive unit, a corresponding gas-sensitive material is arranged on the second electrode group.
Further, the humidity sensitive unit 11 is disposed above the suspension film of the pressure sensitive unit 12.
The multifunctional sensor prepared by the embodiment integrates the temperature sensitive unit 10, the humidity sensitive unit 11/the gas sensitive unit and the pressure sensitive unit 12 on one sensor chip, so that the comprehensive performance of the sensor can be effectively improved. The high-precision temperature-sensitive unit 10 can accurately measure temperature, and the measured temperature parameters can be used for realizing temperature compensation of the pressure-sensitive unit 12 and the humidity-sensitive unit 11/the gas-sensitive unit; secondly, the humidity-sensitive unit 11/gas-sensitive unit can be prepared on the cavity of the pressure-sensitive unit 12, so that the chip size can be reduced, and the cost can be reduced; in addition, the characteristics of poor heat conduction of the sensing suspended film of the pressure sensitive unit 12 are fully utilized by the humidity sensitive unit 11/the gas sensitive unit, and the humidity sensitive unit 11/the gas sensitive unit can be heated under lower power, so that the heating efficiency is improved. The temperature-sensitive unit 10, the humidity-sensitive unit 11/the gas-sensitive unit and the pressure-sensitive unit 12 can be mutually influenced, meanwhile, the process difficulty can be reduced, and the reliability of the sensor can be improved.
In addition, by changing the components of the humidity/gas sensitive material, different humidity/gas sensitive sensors can be prepared, and the application range of the sensor is widened.
In order to further illustrate the preparation flow of the multifunctional sensor provided by the invention, the technical advantages are highlighted, and the embodiment provides the preparation steps of the multifunctional sensor, which specifically comprises the following steps:
step 1: the wafer of the substrate 1 is determined, and the wafer can be cleaned by the RCA method, and the structure of the wafer is shown in fig. 3.
Step 2: a layer of compact silicon oxide 2 film is grown on a wafer of a substrate 1 by adopting a dry oxygen thermal oxidation process, the growth temperature is 900-1100 ℃, the thickness of the film is 50-300 nm, and the structure is shown in figure 4. The silicon oxide 2 film can prevent the channel effect from being generated during the subsequent ion implantation, wherein the channel effect means that most of ions move along a channel when the ions are implanted along the direction of a crystal axis, and the ions are hardly influenced by the scattering of atomic nuclei, and the direction is basically unchanged, so that the silicon oxide 2 film can move far inside a crystal and does not accord with Gaussian distribution. This effect can be significantly improved by growing a thin silicon oxide 2 film on the surface.
Step 3: the preparation of the pressure sensitive cell 12, i.e. the preparation of the piezoresistive strip 3 and the interconnect structure 4, may comprise the steps of:
step 3.1: b+ with a certain concentration is injected into the surface of the wafer by adopting an ion implanter to form P-type piezoresistive strips 3 with consistent resistance;
step 3.2: an ion implanter is used to implant a high concentration of b+ for forming the low internal resistance interconnect structure 4. The interconnect structure 4 connects together several segments of the piezoresistive strips 3 and forms a wheatstone bridge with a fourth set of electrodes 18 made of metallic aluminium 5. In order to reduce the resistance error in the circuit and ohmic contact between aluminum and silicon 5, the internal interconnect structure 4 has a small resistance as much as possible, and thus a high dose high concentration implant is used, and the structure is prepared as shown in fig. 5.
It should be noted that, ion implantation causes damage to the internal structure of the wafer, and most of doped ions are not activated, so that the conductivity is poor, and high-temperature annealing is required, the annealing temperature is 900-1100 ℃, and the annealing time is 30-120 min. After the high temperature anneal, the lattice damage is repaired, and the dopant ions re-diffuse and become activated.
Step 4: the preparation of the fourth electrode set 18, namely, the etching of the aluminum 5 connecting hole and the preparation of the aluminum 5 connecting wire, may specifically include the following steps:
step 4.1: preparing a required pattern on a wafer by photoetching, etching silicon oxide 2 in a connecting hole area by using a BOE solution, and removing photoresist by using a dry method or a wet method to obtain an aluminum 5 connecting hole;
step 4.2: photoetching a wafer to prepare a required pattern, magnetically controlling or evaporating a layer of metal aluminum 5 with the thickness of 1-2 um, and then stripping to prepare a required aluminum 5 connecting wire;
step 4.3: and (3) carrying out alloying annealing, and annealing for 30-60min under vacuum or nitrogen atmosphere at 400-500 ℃ to enable aluminum 5 and silicon to be metallized to form aluminum 5 silicon alloy, so that contact resistance is reduced, and the structure can be shown as shown in figure 6.
Step 5: preparing a protective layer, and preparing a layer of silicon oxide/silicon nitride 6 film with the thickness of 100-300 nm by adopting PECVD (plasma enhanced chemical vapor deposition) as the protective layer for protecting the aluminum 5 electrode and the piezoresistive strip 3. The silicon oxide/silicon nitride 6 with the thickness can fully protect the piezoresistance strip 3 and the aluminum 5 electrode at the lower layer, has smaller stress and has small influence on the performance of the sensor; and the thickness is thinner, the subsequent etching time is shorter, and the overall preparation efficiency of the sensor is improved. The silicon oxide/silicon nitride 6 film in the Pad area can be removed by dry etching to obtain the structure shown in fig. 7.
Step 6: preparation of temperature-sensitive unit 10, second electrode group 16 of humidity-sensitive unit 11, heating unit 13: photoetching a required pattern on a wafer, and then plating a Ti layer and a Pt layer, namely a Ti-Pt layer 7, respectively by adopting magnetron sputtering; the thickness is 0.01-0.5 um and 0.1-5 um respectively, metal Ti is used as an adhesion layer to connect the bottom insulating layer and metal Pt, the metal Pt is used as a second electrode group 16, a temperature sensitive unit 10 and a first electrode group of the humidity sensitive unit 11, and the heating unit 13 and a third electrode group 17 are stripped to obtain the required patterns, as shown in figure 8.
Step 7: preparing a humidity sensing film layer 8 or other sensitive film layers (namely, the gas sensing units correspond to the gas sensing film layers):
the preparation method of the humidity sensing film layer comprises the following steps: on the basis of the structure shown in fig. 8, a layer of prepared moisture-sensitive film is uniformly baked by a nitrogen oven to be solidified, and then a pattern of a needed moisture-sensitive film layer 8 is obtained by adopting a photoetching and dry etching method, as shown in fig. 9. The purpose of using the nitrogen oven is to avoid the air and the moisture-sensitive material from acting in the baking process to influence the performance of the moisture-sensitive material.
The preparation method of the gas-sensitive film layer comprises the following steps: the gas-sensitive material may be prepared onto the moisture-sensitive cell by screen printing or ink-jet printing.
Step 8: the back cavity 9 is prepared on the structure shown in fig. 9 by adopting a dry etching method or a wet etching method, and a sensing suspension film is prepared, and the structure of the sensing suspension film is shown in fig. 10.
Step 9: the peripheral circuit 14 is connected with the electrodes in the structure shown in fig. 10, so that the temperature-sensitive unit 10, the humidity-sensitive unit 11 and the pressure-sensitive unit 12 can be read for feedback data, and the heating unit 13 can be controlled in time.
The multifunctional sensor provided by the embodiment integrates the temperature-sensitive unit 10, the humidity-sensitive unit 11 and the pressure-sensitive unit 12 on one sensor chip, so that the comprehensive performance of the sensor can be effectively improved. The high-precision temperature-sensitive unit 10 can more accurately perform temperature compensation on the pressure-sensitive unit 12 and the humidity-sensitive unit 11; secondly, the humidity-sensitive unit 11 is prepared on the sensing suspension film of the pressure-sensitive unit 12, so that the characteristic of poor heat conduction of the sensing suspension film of the pressure-sensitive unit 12 can be fully utilized, the humidity-sensitive unit 11 can be heated under lower power, and the heating efficiency is improved. The temperature-sensitive unit 10, the humidity-sensitive unit 11 and the pressure-sensitive unit 12 can be mutually influenced, meanwhile, the process difficulty can be reduced, and the reliability of the sensor can be improved.
While the foregoing is directed to the preferred embodiments of the present invention, it will be appreciated by those skilled in the art that changes and modifications may be made without departing from the principles of the invention, such changes and modifications are also intended to be within the scope of the invention.

Claims (10)

1. A multifunctional sensor includes a substrate and peripheral circuitry; the device is characterized by further comprising a temperature-sensitive unit, a humidity-sensitive unit, a pressure-sensitive unit and a heating unit; wherein:
the temperature-sensitive unit is arranged on the substrate and is electrically connected with the peripheral circuit through a first electrode group connected with the temperature-sensitive unit;
the humidity-sensitive unit is arranged on the substrate and is electrically connected with the peripheral circuit through a second electrode group connected with the humidity-sensitive unit;
the heating unit surrounds the humidity-sensitive unit and is arranged on the substrate, and is electrically connected with the peripheral circuit through a third electrode group connected with the heating unit;
the pressure-sensitive unit surrounds the heating unit and is arranged on the substrate, and is electrically connected with the peripheral circuit through a fourth electrode group connected with the pressure-sensitive unit.
2. A multifunctional sensor according to claim 1, characterized in that the pressure sensitive unit comprises a number of segments of piezoresistive strips and a number of interconnecting structures; wherein:
the fourth electrode group is arranged on the piezoresistive strip and connected with the piezoresistive strip;
the piezoresistive strips are sequentially arranged, encircle the periphery of the heating unit and are arranged on the substrate, and the two sections of piezoresistive strips are connected through the interconnection structure;
the interconnection structure connects the piezoresistive strips and forms a Wheatstone bridge with the fourth electrode group.
3. A multifunctional sensor according to claim 2, characterized in that a sensing suspension membrane is arranged on the side of the piezoresistive strip remote from the heating unit, the piezoresistive strip being arranged at the edge of the sensing suspension membrane.
4. A multifunctional sensor according to claim 1, characterized in that a humidity sensitive membrane layer made of a humidity sensitive material is provided on the humidity sensitive unit.
5. A multifunctional sensor according to any one of claims 1-4, characterized in that the humidity sensitive unit is arranged above the pressure sensitive unit suspension membrane.
6. The preparation method of the multifunctional sensor is characterized by comprising the following steps of:
preparing a pressure-sensitive unit and a fourth electrode group on the determined substrate to obtain a first substrate;
plating a Ti-Pt metal film on the first substrate to prepare a temperature sensitive unit, a first electrode group, a second electrode group, a heating unit and a third electrode group, and preparing a humidity sensitive unit to obtain a second substrate; the heating unit is arranged around the humidity-sensitive unit;
and preparing a peripheral circuit electrically connected with the fourth electrode group, the first electrode group, the second electrode group and the third electrode group based on the second substrate so as to complete the preparation of the multifunctional sensor.
7. The method for manufacturing a multifunctional sensor according to claim 6, wherein the step of manufacturing the pressure-sensitive unit and the fourth electrode group on the determined substrate, the step of obtaining the first substrate comprises the following steps:
growing a silicon oxide film on the determined substrate;
arranging a plurality of sections of piezoresistive strips and a plurality of interconnection structures on the surface of a substrate on which a silicon oxide film grows by adopting an ion implanter;
the piezoresistive strips are sequentially arranged, encircle the periphery of the heating unit and are arranged on the substrate, and the two sections of piezoresistive strips are connected through the interconnection structure;
a fourth electrode group connected with the piezoresistive strip is arranged; the interconnection structure connects the piezoresistive strips and forms a Wheatstone bridge with the fourth electrode group.
8. The method for manufacturing a multi-functional sensor according to claim 7, further comprising, after obtaining the second substrate:
and preparing a back cavity on one side of the second substrate far away from the heating unit by adopting a dry etching method or a wet etching method, and preparing a sensing suspension film in the back cavity, wherein the piezoresistive strips are arranged at the edge of the sensing suspension film.
9. The method of manufacturing a multi-functional sensor of claim 6, wherein the preparing the humidity sensitive unit comprises: and arranging a humidity sensing film layer prepared from a humidity sensitive material on the second electrode group so as to finish the preparation of the humidity sensitive unit.
10. The method for manufacturing a multifunctional sensor according to any one of claims 6 to 9, wherein the humidity sensitive unit is disposed above the pressure sensitive unit suspension film.
CN202311302581.XA 2023-10-09 2023-10-09 Multifunctional sensor and preparation method thereof Pending CN117346836A (en)

Priority Applications (1)

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CN202311302581.XA CN117346836A (en) 2023-10-09 2023-10-09 Multifunctional sensor and preparation method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202311302581.XA CN117346836A (en) 2023-10-09 2023-10-09 Multifunctional sensor and preparation method thereof

Publications (1)

Publication Number Publication Date
CN117346836A true CN117346836A (en) 2024-01-05

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Application Number Title Priority Date Filing Date
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Country Status (1)

Country Link
CN (1) CN117346836A (en)

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