CN114544046B - Method for manufacturing pressure sensor - Google Patents
Method for manufacturing pressure sensor Download PDFInfo
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- CN114544046B CN114544046B CN202111581041.0A CN202111581041A CN114544046B CN 114544046 B CN114544046 B CN 114544046B CN 202111581041 A CN202111581041 A CN 202111581041A CN 114544046 B CN114544046 B CN 114544046B
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- silicon wafer
- sensitive resistor
- force sensitive
- flexible film
- silicon
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- 238000000034 method Methods 0.000 title claims abstract description 22
- 238000004519 manufacturing process Methods 0.000 title claims description 13
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 175
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 175
- 239000010703 silicon Substances 0.000 claims abstract description 175
- 239000007888 film coating Substances 0.000 claims abstract description 6
- 238000009501 film coating Methods 0.000 claims abstract description 6
- 229910000881 Cu alloy Inorganic materials 0.000 claims description 21
- YOCUPQPZWBBYIX-UHFFFAOYSA-N copper nickel Chemical compound [Ni].[Cu] YOCUPQPZWBBYIX-UHFFFAOYSA-N 0.000 claims description 21
- 239000000843 powder Substances 0.000 claims description 18
- 239000000758 substrate Substances 0.000 claims description 15
- 239000011248 coating agent Substances 0.000 claims description 11
- 238000000576 coating method Methods 0.000 claims description 11
- 238000004528 spin coating Methods 0.000 claims description 9
- 238000007790 scraping Methods 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 5
- 238000005530 etching Methods 0.000 claims description 4
- 239000002243 precursor Substances 0.000 claims description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 2
- 239000001301 oxygen Substances 0.000 claims description 2
- 229910052760 oxygen Inorganic materials 0.000 claims description 2
- 238000012544 monitoring process Methods 0.000 abstract description 18
- 238000002360 preparation method Methods 0.000 abstract description 10
- 239000010408 film Substances 0.000 description 58
- 238000005516 engineering process Methods 0.000 description 19
- 239000004205 dimethyl polysiloxane Substances 0.000 description 18
- 235000013870 dimethyl polysiloxane Nutrition 0.000 description 18
- CXQXSVUQTKDNFP-UHFFFAOYSA-N octamethyltrisiloxane Chemical compound C[Si](C)(C)O[Si](C)(C)O[Si](C)(C)C CXQXSVUQTKDNFP-UHFFFAOYSA-N 0.000 description 18
- 238000004987 plasma desorption mass spectroscopy Methods 0.000 description 18
- 229920000435 poly(dimethylsiloxane) Polymers 0.000 description 18
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 11
- 238000009826 distribution Methods 0.000 description 11
- 229910052751 metal Inorganic materials 0.000 description 11
- 239000002184 metal Substances 0.000 description 11
- 229910052802 copper Inorganic materials 0.000 description 9
- 239000010949 copper Substances 0.000 description 9
- 239000011521 glass Substances 0.000 description 7
- 229910052759 nickel Inorganic materials 0.000 description 7
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 6
- 238000002156 mixing Methods 0.000 description 6
- 239000010931 gold Substances 0.000 description 5
- 238000001259 photo etching Methods 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 239000003795 chemical substances by application Substances 0.000 description 4
- 238000007872 degassing Methods 0.000 description 4
- 150000002739 metals Chemical class 0.000 description 4
- 239000000178 monomer Substances 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 230000007774 longterm Effects 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000002861 polymer material Substances 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 239000004332 silver Substances 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- FFBHFFJDDLITSX-UHFFFAOYSA-N benzyl N-[2-hydroxy-4-(3-oxomorpholin-4-yl)phenyl]carbamate Chemical compound OC1=C(NC(=O)OCC2=CC=CC=C2)C=CC(=C1)N1CCOCC1=O FFBHFFJDDLITSX-UHFFFAOYSA-N 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 238000005468 ion implantation Methods 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
- 238000000206 photolithography Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 238000010023 transfer printing Methods 0.000 description 1
Classifications
-
- 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
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Pressure Sensors (AREA)
- Measuring Fluid Pressure (AREA)
Abstract
The application relates to a pressure sensor, which comprises a silicon wafer and a flexible film, wherein one side of the silicon wafer is provided with at least one force sensitive resistor, the flexible film coats the silicon wafer, and the thickness of the flexible film is larger than or equal to that of the silicon wafer. The application also relates to a preparation method of the pressure sensor, a silicon wafer is provided, and one side of the silicon wafer is provided with at least one force sensitive resistor; and forming a flexible film coating the silicon wafer to obtain the pressure sensor. According to the method, the force sensitive element made of the silicon wafer is embedded in the flexible film, so that the flexibility of the device can be improved, the pressure interference of the device to the monitoring environment is reduced, and the accurate monitoring of the contact interface pressure can be realized.
Description
Technical Field
The application relates to the technical field of pressure sensors, in particular to a preparation method of a pressure sensor.
Background
The basic principle of measuring the contact pressure between two objects is to string a force sensitive element into the force system structure, and the intervention of the force sensitive element will change the environment of the measured system. However, in the prior art, the pressure sensor based on the silicon wafer is generally prepared on the surface of the substrate, so that the whole thickness of the device is larger, the flexibility is poorer, the pressure interference of the pressure sensor on the monitoring environment is stronger, and the accurate monitoring of the contact interface pressure is difficult to realize.
Disclosure of Invention
According to the technical problem, the preparation method of the pressure sensor is provided, the force sensitive element made of the silicon wafer is embedded in the flexible film, so that the flexibility of the device can be improved, the pressure interference of the device to the monitoring environment is reduced, and the accurate monitoring of the contact interface pressure can be realized.
In order to solve the technical problem, the application provides a pressure sensor, which comprises a silicon wafer and a flexible film, wherein one side of the silicon wafer is provided with at least one force sensitive resistor, the flexible film is coated on the silicon wafer, and the thickness of the flexible film is larger than or equal to that of the silicon wafer.
Optionally, a cavity is arranged on the other side of the silicon wafer, and the force sensitive resistor is located in a projection area of the cavity along the thickness direction of the silicon wafer.
Optionally, the depth of the cavity is 2-5 μm, the thickness of the flexible film is 5-10 μm, and the thickness of the silicon wafer is less than 10 μm.
Optionally, a circuit is arranged on the surface of one side of the flexible film, which corresponds to the force sensitive resistor, and one end of the circuit is connected with the force sensitive resistor.
The application also provides a preparation method of the pressure sensor, which comprises the following steps:
a. providing a silicon wafer, wherein one side of the silicon wafer is provided with at least one force sensitive resistor;
b. and forming a flexible film coating the silicon wafer to obtain the pressure sensor.
Optionally, the step a includes:
a1. providing an SOI silicon wafer, wherein an oxygen burying layer of the SOI silicon wafer separates the SOI silicon wafer into upper-layer silicon and lower-layer silicon;
a2. forming at least one force sensitive resistor on one side surface of the upper silicon layer;
a3. and etching to remove the buried oxide layer to obtain upper silicon containing the force sensitive resistor as the silicon wafer.
Optionally, the a2 step includes:
a21. uniformly scraping nickel-copper alloy powder on the upper surface of the SOI silicon wafer;
a22. and melting nickel-copper alloy powder positioned in a designated area through laser direct writing to form a uniform conductive layer, thereby obtaining the force-sensitive resistor.
Optionally, the step b includes:
b1. transferring the silicon wafer separated from the underlying silicon by a substrate having a flexible coating, contacting a side of the silicon wafer having the force sensitive resistor with the flexible coating;
b2. and spin-coating a precursor solution of a high molecular material on the surface of the side, provided with the silicon wafer, of the substrate, and then curing to form the flexible film.
Optionally, after the step b2, the method further includes:
b3. and forming a cavity on one side of the silicon wafer far away from the force sensitive resistor, so that the force sensitive resistor is positioned in a projection area of the cavity along the thickness direction of the silicon wafer.
Optionally, the step b further includes:
b4. peeling the flexible film and the silicon wafer from the substrate;
b5. and manufacturing a circuit on one side of the flexible film, which corresponds to the force sensitive resistor, so that one end of the circuit is connected with the force sensitive resistor.
The pressure sensor comprises a silicon wafer and a flexible film, wherein one side of the silicon wafer is provided with at least one force sensitive resistor, the flexible film coats the silicon wafer, and the thickness of the flexible film is larger than or equal to that of the silicon wafer. The application also relates to a preparation method of the pressure sensor, a silicon wafer is provided, and one side of the silicon wafer is provided with at least one force sensitive resistor; and forming a flexible film coating the silicon wafer to obtain the pressure sensor. According to the method, the force sensitive element made of the silicon wafer is embedded in the flexible film, so that the flexibility of the device can be improved, the pressure interference of the device to the monitoring environment is reduced, and the accurate monitoring of the contact interface pressure can be realized.
Drawings
Fig. 1 is a schematic structural view of a pressure sensor shown according to a first embodiment;
FIG. 2 is a flow chart illustrating a method of manufacturing a pressure sensor according to a second embodiment;
fig. 3 is a process schematic diagram of a method of manufacturing a pressure sensor according to a second embodiment.
Detailed Description
Further advantages and effects of the present application will be readily apparent to those skilled in the art from the present disclosure, by describing the embodiments of the present application with specific examples.
In the following description, reference is made to the accompanying drawings, which describe several embodiments of the present application. It is to be understood that other embodiments may be utilized and that mechanical, structural, electrical, and operational changes may be made without departing from the spirit and scope of the present application. The following detailed description is not to be taken in a limiting sense, and the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
Although the terms first, second, etc. may be used herein to describe various elements in some examples, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element.
Furthermore, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes," and/or "including" specify the presence of stated features, steps, operations, elements, components, items, categories, and/or groups, but do not preclude the presence, presence or addition of one or more other features, steps, operations, elements, components, items, categories, and/or groups. The terms "or" and/or "as used herein are to be construed as inclusive, or meaning any one or any combination. Thus, "A, B or C" or "A, B and/or C" means "any of the following: a, A is as follows; b, a step of preparing a composite material; c, performing operation; a and B; a and C; b and C; A. b and C). An exception to this definition will occur only when a combination of elements, functions, steps or operations are in some way inherently mutually exclusive.
First embodiment
Fig. 1 is a schematic structural view of a pressure sensor according to a first embodiment. As shown in fig. 1, the pressure sensor of the present embodiment includes a silicon wafer 10 and a flexible film 11, and at least one force sensitive resistor 12 is provided on one side of the silicon wafer 10. The flexible film 11 coats the silicon wafer 10, and the thickness of the flexible film 11 is greater than or equal to the thickness of the silicon wafer 10.
According to the pressure sensor, the force sensitive element is embedded in the flexible film through the embedding technology, so that the formed pressure sensor has good flexibility, the pressure interference of the device to the monitoring environment is reduced, and the accurate monitoring of the contact interface pressure can be realized.
In this embodiment, the Silicon wafer 10 is made of an SOI (Silicon-On-Insulator) Silicon wafer. The buried oxide layer of the SOI silicon wafer separates the SOI silicon wafer into an upper silicon layer and a lower silicon layer, and the thickness of the upper silicon layer in the SOI silicon wafer is smaller than that of the lower silicon layer. In this example, after removing the buried oxide layer by etching, an ultra-thin upper layer silicon was obtained as the silicon wafer 10. Preferably, the thickness of the silicon wafer 10 is less than 10 μm. Therefore, the silicon chip is embedded in the flexible film, so that the ultrathin flexible pressure sensor is realized, the device has good flexibility, the pressure monitoring of environments such as curved surfaces, narrow gaps and the like can be realized, and the gap contact is hardly influenced.
The distribution position of the force sensitive resistor 12 is determined according to the stress strain distribution state of the surface of the silicon wafer 10, and the stress strain distribution state of the surface of the silicon wafer 10 can be obtained through simulation analysis of a mechanical model. Alternatively, a laser direct writing technique may be used to fabricate a metal electrode on one side surface of the silicon wafer 10 as the force sensitive resistor 12. Specifically, the metal powder or alloy powder may be uniformly drawn on the upper surface of the silicon wafer 10, and then the metal powder or alloy powder located in a designated area for forming the force-sensitive resistor 12 is melted by a laser direct writing technique to form a uniform conductive layer, thereby obtaining the force-sensitive resistor 12. The force sensitive resistor 12 may be made of copper, silver, nickel, or other metals or alloys. The nickel-copper alloy is sensitive to stress change and insensitive to temperature change, and preferably the nickel-copper alloy, wherein the mass fraction of nickel is 20% -55% and the mass fraction of copper is 45% -80%.
Alternatively, a cavity 101 may be provided on the side of the silicon wafer 10 remote from the force-sensitive resistor 12, the force-sensitive resistor 12 being located in a projection area of the cavity 101 in the thickness direction of the silicon wafer 10. The shape of the cavity 101 may be matched to the shape of the wafer 10, such as circular or rectangular. Preferably, the position of the flexible film 11 corresponding to the cavity 101 is hollowed out, i.e. the area where the cavity 101 is not covered by the flexible film 11.
The thickness of the silicon wafer 10 in the region corresponding to the force sensitive resistor 12 in the silicon wafer 10 is further thinned by the cavity 101, so that the deformation degree of the pressure sensor is increased when the pressure sensor is stressed, and the pressure measuring sensitivity of the device is improved.
Alternatively, the depth of the cavity 101 is 2 μm to 5 μm, the thickness of the flexible film 11 is 5 μm to 10 μm, and the thickness of the silicon wafer 10 is less than or equal to 10 μm, so that the overall thickness of the device is less than or equal to 10 μm, and better flexibility can be obtained.
Optionally, a circuit 13 is provided on a surface of the flexible film 11 on a side corresponding to the force sensitive resistor 12, and one end of the circuit 13 is connected to the force sensitive resistor 12. Since the side of the silicon wafer 10 having the force sensitive resistor 12 is connected to the flexible film 11 in a continuous plane, the circuit 13 can be prepared by using a photolithography technique to output a signal of the force sensitive resistor 12. The material of the circuit 13 may be gold, copper, aluminum, or other metals.
The pressure sensor comprises a silicon wafer and a flexible film, wherein one side of the silicon wafer is provided with at least one force sensitive resistor, the flexible film coats the silicon wafer, and the thickness of the flexible film is larger than or equal to that of the silicon wafer. According to the method, the force sensitive element made of the silicon wafer is embedded in the flexible film, so that the flexibility of the device can be improved, the pressure interference of the device to the monitoring environment is reduced, and the accurate monitoring of the contact interface pressure can be realized.
Second embodiment
Fig. 2 is a flow chart illustrating a method of manufacturing a pressure sensor according to a second embodiment. As shown in fig. 2, the method for manufacturing the pressure sensor of the present embodiment includes the following steps:
step a, providing a silicon wafer, wherein one side of the silicon wafer is provided with at least one force sensitive resistor.
Optionally, in step a, the method includes:
step a1. As shown in fig. 3 (a), an SOI wafer is provided, which includes an upper layer silicon 21, a buried oxide layer 22, and a lower layer silicon 23. The buried oxide layer 22 separates the SOI silicon wafer into an upper silicon 21 and a lower silicon 23, the thickness of the upper silicon 21 in the SOI silicon wafer being smaller than the thickness of the lower silicon 23, the thickness of the upper silicon 21 being smaller than or equal to 10 μm.
Step a2. As shown in fig. 3 (b), at least one force sensitive resistor 31 is formed on one side surface of the upper layer silicon 21.
Optionally, in step a2, further includes:
and a21, uniformly scraping nickel-copper alloy powder on the upper surface of the SOI silicon wafer.
Step a22, melting nickel-copper alloy powder positioned in a designated area by laser direct writing to form a uniform conductive layer, thereby obtaining the force sensitive resistor 31.
Step a3. Etching to remove the buried oxide layer 22 to obtain the upper silicon layer 21 containing the force sensitive resistor 31 as a silicon wafer.
In this embodiment, the surface stress strain distribution state of the upper layer silicon 21 in the SOI wafer is analyzed by a mechanical model to determine the distribution position of the force sensitive resistor 31 on the surface of the upper layer silicon 21, and then the force sensitive resistor 31 is formed by directly writing a metal electrode on the surface of the upper layer silicon 21 by using a laser direct writing technology. The material of the force sensitive resistor 31 can be silver, copper, nickel, or other metals or metal alloys. Since the nickel-copper alloy is sensitive to stress variation and is correspondingly insensitive to temperature variation, the nickel-copper alloy is preferably used for manufacturing the force-sensitive resistor 31, wherein the mass fraction of nickel is 20% -55%, and the mass fraction of copper is 45% -80%. Specifically, nickel-copper alloy powder is uniformly scraped on the surface of the upper silicon layer 21, then a laser direct writing technology is adopted to prepare the force-sensitive resistor 31, and the nickel-copper alloy powder is melted under the action of laser heat to form a uniform conductive layer as the force-sensitive resistor 31. The laser has a laser wavelength of 355-1064 nm, a power range of 1-20W, a scanning speed of 50-2000 mm/s, a scanning frequency of 1-20, and a laser with a wavelength of 1064nm, and the laser can be used for realizing melting and cladding of metal powder on the surface of a silicon wafer by utilizing the photo-thermal effect of the laser, so that the conductivity of the metal powder and the bonding force between the metal powder and the silicon wafer are improved.
The SOI silicon wafer is etched by using the BOE solution, and the buried oxide layer 22 of the SOI silicon wafer is etched and removed to obtain the upper silicon layer 21 including the force sensitive resistor 31 as a silicon wafer (i.e., the silicon wafer 30 shown in FIG. 3 (e)).
And b, forming a flexible film coating the silicon wafer to obtain the pressure sensor.
Optionally, as shown in (e) of fig. 3, in step b, it includes:
step b1. The silicon wafer 30 separated from the underlying silicon is transferred through the substrate 40 having the flexible coating 41, and the side of the silicon wafer 30 having the force sensitive resistor 31 is brought into contact with the flexible coating 41.
In this embodiment, as shown in fig. 3 (c), a substrate 40 is provided, and the substrate 40 may be a clean glass sheet. As shown in fig. 3 (d), the flexible coating 41 on the substrate 40 may be a PDMS film, specifically, a PDMS monomer and a curing agent are mixed according to 10:1, spin-coating the surface of the substrate 40 after degassing, and curing at 80-200 ℃ for 0.5-6 hours to form a PDMS film, namely the flexible coating 41. As shown in fig. 3 (e), the silicon wafer 30 is transferred to the surface of the flexible coating 41, and the side of the silicon wafer 30 having the force sensitive resistor 31 is in contact with the flexible coating 41.
Step b2. As shown in fig. 3 (f), a precursor solution of a polymer material is spin-coated on the surface of the substrate 40 on the side having the silicon wafer 30 and then cured, so as to form the flexible thin film 32.
In this embodiment, PI solution is selected as the precursor solution of the polymer material. The PI solution is spin-coated on the surface of the substrate 40 with the silicon wafer 30 at the speed of 2000-4000 rmp, and the PI solution is cured for 0.5-3 hours at the temperature of 80-250 ℃ to form the flexible film 32, so that the silicon wafer is embedded in the flexible film 32, and the overall flexibility of the device is improved.
Optionally, as shown in fig. 3 (g), after step b2, the method further includes:
step b3. A cavity 301 is formed on the side of the silicon wafer 30 away from the force sensitive resistor 31, such that the force sensitive resistor 31 is located in a projection area of the cavity 301 along the thickness direction of the silicon wafer 30.
In this embodiment, a cavity 301 is etched on the upper surface of the flexible film 32 by using a laser scanning technique, and the cavity 301 may have a circular shape. Wherein the thickness of the flexible film 32 is 5-10 μm, the depth of the cavity is 2-5 μm, and the laser parameters are as follows: the wavelength is 355-1064 nm, the power range is 1-20W, and the scanning speed is 50-2000 mm/s.
The thickness of the silicon wafer 30 in the region corresponding to the force sensitive resistor 31 in the silicon wafer 30 is further thinned by the cavity 301, so that the deformation degree of the pressure sensor is increased when the pressure sensor is stressed, and the pressure measuring sensitivity of the device is improved.
Optionally, as shown in (g) and (h) in fig. 3, step b further includes:
step b4. The flexible film 32 and the silicon wafer 30 are peeled off the substrate 40.
And b5, manufacturing a circuit 33 on one side of the flexible film 32 corresponding to the force sensitive resistor 31, and connecting one end of the circuit 33 with the force sensitive resistor 31.
In this embodiment, the flexible film 32 with the silicon wafer 30 is peeled off from the surface of the flexible coating 41. The circuit 33 may then be prepared using photolithographic techniques to output the signal generated by the force sensitive resistor 31. The material of the circuit 13 may be gold, copper, aluminum, or other metals.
The method for preparing the pressure sensor by combining the laser direct writing technology and the transfer printing technology utilizes the characteristics of high efficiency, high selectivity and high precision of the laser direct writing technology to prepare the force-sensitive resistor, overcomes the defects of complex process, high cost, environmental pollution and the like in the traditional photoetching technology (steps of ion implantation, photoetching and the like), and realizes the rapid and low-cost preparation of the force-sensitive resistor.
The following describes the method of manufacturing the pressure sensor of the present application by specifically listing three processes.
Process 1:
(1) Preparing a force sensitive resistor: analyzing the stress strain distribution state of the surface of the silicon wafer through a mechanical model, determining that the force-sensitive resistor is in a cross distribution state on the surface of the silicon wafer, adopting a laser direct-writing technology to directly write nickel-copper alloy on the surface of the SOI silicon wafer as the force-sensitive resistor, uniformly scraping nickel-copper alloy powder (mass fraction: 45% Ni and 55% Cu) on the surface of the SOI silicon wafer, then adopting the laser direct-writing technology to prepare the force-sensitive resistor, wherein the laser wavelength is 1064nm, the power range is 10W, the scanning speed is 50 mm/s, the scanning times are 1, and the nickel-copper alloy resistor bar graph is formed.
(2) Force sensitive resistance transfer: mixing PDMS monomer and curing agent according to the weight ratio of 10:1, uniformly mixing, spin-coating on the surface of a clean glass sheet after degassing, curing for 6 hours at the temperature of 80 ℃ to form a PDMS film, then adopting a BOE solution to corrode the step (1) to prepare the SOI silicon wafer with the power-sensitive resistor, transferring the upper silicon (10 mu m) onto the surface of the PDMS film after the oxygen-buried layer in the middle of the SOI silicon wafer is corroded and removed, and enabling the power-sensitive resistor side in the silicon wafer to be in contact with the PDMS film.
(3) Preparing a cavity: and (3) spin-coating PI solution on the surface of the glass sheet with the silicon wafer side, curing for 0.5h at the temperature of 250 ℃ at the speed of 2000rmp to form a flexible film, and embedding the silicon wafer in the flexible film. Then, a circular cavity structure is etched on the upper surface of the silicon wafer by adopting a laser scanning technology, the thickness of the silicon wafer is 10 mu m, the depth of the cavity is 5 mu m, and the laser parameters are as follows: the wavelength was 355 nm, the power range was 2W, and the scanning speed was 500 mm/s.
(4) The preparation of the circuit comprises the following steps: and peeling the flexible film from the surface of the PDMS film, preparing an Au conductive line by adopting a photoetching technology, outputting a signal generated by a force-sensitive resistor, and finally preparing the flexible pressure sensor with the thickness of about 10 mu m, thereby being suitable for long-term real-time monitoring of narrow-gap pressure.
Process 2:
(1) Preparing a force sensitive resistor: analyzing the stress strain distribution state of the surface of the silicon wafer through a mechanical model, determining that the force-sensitive resistor is in a cross distribution state on the surface of the silicon wafer, adopting a laser direct-writing technology to directly write nickel-copper alloy on the surface of the SOI silicon wafer as the force-sensitive resistor, uniformly scraping nickel-copper alloy powder (mass fraction: 20% Ni and 80% Cu) on the surface of the SOI silicon wafer, then adopting the laser direct-writing technology to prepare the force-sensitive resistor, wherein the laser wavelength is 532 nm, the power range is 15W, the scanning speed is 100 mm/s, the scanning times are 3, and the nickel-copper alloy resistor bar graph is formed.
(2) Force sensitive resistance transfer: mixing PDMS monomer and curing agent according to the weight ratio of 10:1, uniformly mixing, spin-coating on the surface of a clean glass sheet after degassing, curing for 6 hours at the temperature of 80 ℃ to form a PDMS film, then adopting a BOE solution to corrode the step (1) to prepare the SOI silicon wafer with the powerful thermistor, and transferring the upper silicon layer to the surface of the PDMS film after the oxygen-buried layer in the middle of the SOI silicon wafer is corroded and removed, wherein the force-sensitive resistor side in the silicon wafer is in contact with the PDMS film.
(3) Preparing a cavity: and (3) spin-coating PI solution on the surface of the glass sheet with the silicon wafer side, curing for 0.5h at the temperature of 250 ℃ at the speed of 2000rmp to form a flexible film, and embedding the silicon wafer in the flexible film. Then, a circular cavity structure is etched on the upper surface of the silicon wafer by adopting a laser scanning technology, the thickness of the silicon wafer is 5 mu m, the depth of the cavity is 2 mu m, and the laser parameters are as follows: the wavelength was 355 nm, the power range was 2W, and the scanning speed was 500 mm/s.
(4) The preparation of the circuit comprises the following steps: and stripping the flexible film I from the surface of the PDMS film, preparing an Au conductive line by adopting a photoetching technology, outputting a signal generated by a force-sensitive resistor, and finally preparing the flexible pressure sensor with the thickness of about 5 mu m, thereby being suitable for long-term real-time monitoring of narrow-gap pressure.
And 3, process 3:
(1) Preparing a force sensitive resistor: analyzing the stress strain distribution state of the surface of the silicon wafer through a mechanical model, determining that the force-sensitive resistor is in a cross distribution state on the surface of the silicon wafer, adopting a laser direct-writing technology to directly write nickel-copper alloy on the surface as the force-sensitive resistor, uniformly scraping nickel-copper alloy powder (mass fraction: 50% Ni and 50% Cu) on the surface of the SOI silicon wafer, then adopting the laser direct-writing technology to prepare the force-sensitive resistor, wherein the laser wavelength is 355 nm, the power range is 20W, the scanning speed is 200 mm/s, the scanning times are 10, and the nickel-copper alloy resistor bar graph is formed.
(2) Force sensitive resistance transfer: mixing PDMS monomer and curing agent according to the weight ratio of 10:1, uniformly mixing, spin-coating on the surface of a clean glass sheet after degassing, curing for 2 hours at the temperature of 150 ℃ to form a PDMS film, then adopting a BOE solution to corrode the step (1) to prepare the SOI silicon wafer with the powerful thermistor, and transferring the upper silicon layer to the surface of the PDMS film after the oxygen-buried layer in the middle of the SOI silicon wafer is corroded and removed, wherein the force-sensitive resistor side of the silicon wafer is in contact with the PDMS film.
(3) Preparing a cavity: and (3) spin-coating PI solution on the surface of the glass sheet with the silicon wafer side, curing for 0.5h at the temperature of 250 ℃ at the speed of 2000rmp to form a flexible film, and embedding the silicon wafer in the flexible film. Then, a circular cavity structure is etched on the upper surface of the silicon wafer by adopting a laser scanning technology, the thickness of the silicon wafer is 8 mu m, the depth of the cavity is 4 mu m, and the laser parameters are as follows: the wavelength was 355 nm, the power range was 2W, and the scanning speed was 500 mm/s.
(4) The preparation of the circuit comprises the following steps: and peeling the flexible film from the surface of the PDMS film, preparing an Au conductive line by adopting a photoetching technology, outputting a signal generated by a force-sensitive resistor, and finally preparing the flexible pressure sensor with the thickness of about 8 mu m, thereby being suitable for long-term real-time monitoring of narrow-gap pressure.
The preparation method of the pressure sensor comprises the following steps: providing a silicon wafer, wherein one side of the silicon wafer is provided with at least one force sensitive resistor; and forming a flexible film coating the silicon wafer to obtain the pressure sensor. According to the method, the force sensitive element made of the silicon wafer is embedded in the flexible film, so that the flexibility of the device can be improved, the pressure interference of the device to the monitoring environment is reduced, and the accurate monitoring of the contact interface pressure can be realized.
The foregoing embodiments are merely illustrative of the principles of the present application and their effectiveness, and are not intended to limit the application. Modifications and variations may be made to the above-described embodiments by those of ordinary skill in the art without departing from the spirit and scope of the present application. Accordingly, it is intended that all equivalent modifications and variations which may be accomplished by persons skilled in the art without departing from the spirit and technical spirit of the disclosure be covered by the claims of this application.
Claims (2)
1. A method of manufacturing a pressure sensor, comprising the steps of:
a. providing a silicon wafer, wherein one side of the silicon wafer is provided with at least one force sensitive resistor;
b. forming a flexible film coating the silicon wafer to obtain the pressure sensor;
the step a comprises the following steps:
a1. providing an SOI silicon wafer, wherein an oxygen burying layer of the SOI silicon wafer separates the SOI silicon wafer into upper-layer silicon and lower-layer silicon;
a2. forming at least one force sensitive resistor on one side surface of the upper silicon layer;
a3. etching to remove the buried oxide layer to obtain upper silicon containing the force sensitive resistor as the silicon wafer;
the a2 step comprises:
a21. uniformly scraping nickel-copper alloy powder on the upper surface of the SOI silicon wafer;
a22. the nickel-copper alloy powder positioned in the designated area is melted by laser direct writing to form a uniform conductive layer, so that the force-sensitive resistor is obtained;
the step b comprises the following steps:
b1. transferring the silicon wafer separated from the underlying silicon by a substrate having a flexible coating, contacting a side of the silicon wafer having the force sensitive resistor with the flexible coating;
b2. spin-coating a precursor solution of a high molecular material on the surface of the side of the substrate with the silicon wafer, and then curing to form the flexible film;
after the step b2, the method further comprises:
b3. and forming a cavity on one side of the silicon wafer far away from the force sensitive resistor, so that the force sensitive resistor is positioned in a projection area of the cavity along the thickness direction of the silicon wafer.
2. The method of manufacturing a pressure sensor according to claim 1, wherein the step b further comprises:
b4. peeling the flexible film and the silicon wafer from the substrate;
b5. and manufacturing a circuit on one side of the flexible film, which corresponds to the force sensitive resistor, so that one end of the circuit is connected with the force sensitive resistor.
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