CN116678544B - Silicon strain gauge and manufacturing method thereof - Google Patents
Silicon strain gauge and manufacturing method thereof Download PDFInfo
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- CN116678544B CN116678544B CN202310975186.1A CN202310975186A CN116678544B CN 116678544 B CN116678544 B CN 116678544B CN 202310975186 A CN202310975186 A CN 202310975186A CN 116678544 B CN116678544 B CN 116678544B
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 93
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 93
- 239000010703 silicon Substances 0.000 title claims abstract description 93
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 28
- 239000002184 metal Substances 0.000 claims abstract description 70
- 238000005530 etching Methods 0.000 claims description 24
- 238000002161 passivation Methods 0.000 claims description 24
- 238000005516 engineering process Methods 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 17
- 229910001220 stainless steel Inorganic materials 0.000 claims description 12
- 239000010935 stainless steel Substances 0.000 claims description 12
- 229910004205 SiNX Inorganic materials 0.000 claims description 9
- 230000008569 process Effects 0.000 claims description 9
- 229920001971 elastomer Polymers 0.000 claims description 8
- 239000000806 elastomer Substances 0.000 claims description 8
- 238000005468 ion implantation Methods 0.000 claims description 7
- 239000002002 slurry Substances 0.000 claims description 7
- 229910052796 boron Inorganic materials 0.000 claims description 6
- -1 boron ions Chemical class 0.000 claims description 6
- 150000002500 ions Chemical class 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 6
- 238000007740 vapor deposition Methods 0.000 claims description 6
- 238000000137 annealing Methods 0.000 claims description 5
- 238000004806 packaging method and process Methods 0.000 claims description 5
- 238000001259 photo etching Methods 0.000 claims description 5
- 238000012360 testing method Methods 0.000 claims description 4
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 3
- 238000005260 corrosion Methods 0.000 claims description 3
- 230000007797 corrosion Effects 0.000 claims description 3
- 229910000040 hydrogen fluoride Inorganic materials 0.000 claims description 3
- 238000004544 sputter deposition Methods 0.000 claims description 3
- 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
- 238000000926 separation method Methods 0.000 claims description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims 6
- 229910052681 coesite Inorganic materials 0.000 claims 3
- 229910052906 cristobalite Inorganic materials 0.000 claims 3
- 239000000377 silicon dioxide Substances 0.000 claims 3
- 235000012239 silicon dioxide Nutrition 0.000 claims 3
- 229910052682 stishovite Inorganic materials 0.000 claims 3
- 229910052905 tridymite Inorganic materials 0.000 claims 3
- 238000010586 diagram Methods 0.000 description 15
- 239000011521 glass Substances 0.000 description 15
- 238000002844 melting Methods 0.000 description 11
- 239000000758 substrate Substances 0.000 description 6
- 229910004298 SiO 2 Inorganic materials 0.000 description 5
- 241001391944 Commicarpus scandens Species 0.000 description 2
- 238000011068 loading method Methods 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 238000004378 air conditioning Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000002146 bilateral effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000004518 low pressure chemical vapour deposition Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000005057 refrigeration Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
Classifications
-
- 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
- G01L9/04—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 resistance-strain gauges
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Abstract
The application relates to the technical field of silicon strain gauges and discloses a silicon strain gauge and a manufacturing method thereof. And two ends of the stress sensitive structure are respectively connected with the corresponding supporting frame structure and the middle pick-up structure. Each stress sensitive structure comprises two parallel stress sensitive beams, and a support beam is arranged between the two stress sensitive beams; at least one sensitive resistor is arranged on each stress sensitive beam along the length direction of the stress sensitive beam, and the sensitive resistors are connected through metal connecting wires. The pick-up structure is provided with a metal bonding pad for leading out an electric signal. The sensing resistors on the two sensing structures and the metal pads on the pick-up structure are connected to form a wheatstone half bridge. The stress sensitive structure is positioned in the center of the supporting frame, so that the stress sensitive structure can be protected from being damaged; a supporting beam with enhanced strength is arranged between the stress sensitive beams, so that the probability of breakage of sensitive resistors can be reduced.
Description
Technical Field
The application relates to the technical field of silicon strain gauges, in particular to a silicon strain gauge and a manufacturing method thereof.
Background
The silicon strain gauge is a core of a glass micro-melting pressure sensor, is integrated with a stainless steel sensitive elastomer through a high-temperature sintering process, and can realize measurement of pressure of various gases, liquids and other media compatible with stainless steel. The glass micro-melting pressure sensor adopting the silicon strain gauge technology has the advantages of no hysteresis, high sensitivity, good stability and the like, and is widely applied to industries such as engineering machinery, automobiles, ship manufacturing, food processing, petrochemical industry, air conditioning refrigeration and the like.
The silicon strain gauge adopted by the prior glass micro-melting pressure sensor is generally in the hollow structure form shown in fig. 1. In order to ensure that the glass micro-fusion sensor has higher sensitivity, the thickness of the silicon strain gauge is very thin, usually lower than 100um; in addition, the silicon strain gauge is made of monocrystalline silicon material, and silicon is a brittle material, so that the ductility is poor. Therefore, the existing silicon strain gauge with a thinner hollow structure is very fragile, and particularly a sensitive resistance area for stress detection is easy to break, so that the sensor is invalid.
In addition, the existing silicon strain gauge is very fragile, so that automatic picking of equipment is difficult to realize during packaging, and precision, consistency and the like of a chip mounting position are also difficult to ensure, so that the precision of the glass micro-melting pressure sensor is reduced. With the continuous expansion of the application amount of the glass micro-melting pressure sensor, the defects of the existing silicon strain gauge are more remarkable.
Disclosure of Invention
In view of the shortcomings of the background technology, the application provides a silicon strain gauge and a manufacturing method thereof, and aims to solve the technical problems that the existing silicon strain gauge is of a hollowed-out structure, is easy to break and difficult to pick up, and the assembly precision and consistency are difficult to ensure, so that the precision of a glass micro-melting pressure sensor can be reduced.
In order to solve the technical problems, in a first aspect, the application provides a silicon strain gauge, which comprises a body, wherein a first supporting frame, a pick-up part and a second supporting frame are sequentially arranged on the body along the length direction of the body, the first supporting frame and the second supporting frame are supporting structures, stress sensitive structures are arranged on the first supporting frame and the second supporting frame, each stress sensitive structure comprises two parallel stress sensitive beams fixed on the inner wall of the supporting frame, the length direction of each stress sensitive beam is the same as the length direction of the body, M supporting beams are arranged between the two stress sensitive beams on each supporting frame, and M is a positive integer;
at least one sensitive resistor is arranged on each stress sensitive beam along the length direction of the stress sensitive beam, and the sensitive resistors on the two stress sensitive beams on each supporting frame are connected through a connecting wire;
the pick-up part is provided with a metal electrode for transmitting sensitive resistance signals.
In a certain implementation manner of the first aspect, two parallel sensitive resistors are arranged on each stress sensitive beam;
the sensitive resistors on the two pressure sensitive beams on each support frame are electrically connected through at least two connecting wires.
In certain embodiments of the first aspect, M is a positive integer greater than 1, and all support beams divide the stress sensitive beam into equally spaced m+1 sections.
In a certain embodiment of the first aspect, the metal electrode includes a first metal electrode, a second metal electrode and a third metal electrode, two stress sensitive beams on the support frame are used as front stress sensitive beams and rear stress sensitive beams, the first metal electrode is electrically connected with the sensitive resistors on the two front stress sensitive beams, the second metal electrode is electrically connected with the sensitive resistor on one rear stress sensitive beam, and the third metal electrode is electrically connected with the sensitive resistor on the other rear stress sensitive beam.
In certain embodiments of the first aspect, the application further comprises a stainless steel elastomer to which the body is secured by a layer of sintered slurry.
In a second aspect, the present application also provides a method for manufacturing a silicon strain gauge, comprising the steps of:
s1: implanting ions into the top surface of the SOI silicon wafer by an ion implantation technology to manufacture a P-type potential layer;
s2: manufacturing an N-type epitaxial layer on the top surface of the P-type potential layer through an epitaxial technology;
s3: ion implantation technology is used for implanting ions on the top surface of the N-type epitaxial layer to manufacture a sensitive resistor;
s4: manufacturing a dielectric layer covering the sensitive resistor on the N-type epitaxial layer by a vapor deposition technology;
s5: etching a lead hole for leading out the sensitive resistor on the dielectric layer by an etching technology;
s6: sputtering metal on the dielectric layer to form a metal layer, and carrying out photoetching, etching or corrosion on the metal layer to form a metal connecting wire between sensitive resistors and a metal electrode for packaging or testing;
s7: growing a passivation layer on the dielectric layer by a vapor deposition technology, wherein the passivation layer covers the metal connecting wire and the metal electrode;
s8: photoetching and etching a bonding pad area of the metal electrode on the passivation layer;
s9: etching a supporting structure and a stress sensitive structure on the device after the step S8 is executed, and etching scribing grooves among all silicon strain gauges on the SOI silicon wafer;
s10: and removing the buried oxide layer of the SOI silicon wafer by adopting a gaseous HF release process, so that each silicon strain gauge on the wafer is separated from the substrate of the SOI silicon wafer, and the separated silicon strain gauge is obtained.
In certain embodiments of the second aspect, the P-type potential layer is formed in step S1 by implanting boron ions into the top surface of the SOI wafer, and then annealing the SOI wafer; in step S3, the sensitive resistor is fabricated by implanting boron ions on the top surface of the N-type epitaxial layer, and then annealing the device.
In one embodiment of the second aspect, the dielectric layer is made of SiO 2 And SiNx, the SiO 2 The thickness of the film is between 0.2um and 0.3 um; the thickness of the SiNx is between 0.1um and 0.15 um;
the passivation layer is made of SiO 2 The thickness of the passivation layer is between 0.4um and 0.6 um; or the passivation layer is made of SiNx, and the thickness of the passivation layer is between 0.2um and 0.3 um.
In a certain embodiment of the second aspect, the sensing resistors in step S3 include two front sensing resistors and two rear sensing resistors, the two front sensing resistors are arranged in parallel, the two rear sensing resistors are arranged in parallel, and the metal connecting wire manufactured in step S6 is electrically connected with the two front sensing resistors and the two rear sensing resistors respectively.
In a certain embodiment of the second aspect, in step S9, the supporting structure and the stress sensitive structure are etched by a MEMS deep silicon etching process, and the stop layer of this etching is an oxygen buried layer of the SOI silicon wafer;
in the step S10, the buried oxide layer of the SOI silicon wafer is removed by a gaseous hydrogen fluoride etching process, so that the separation of the silicon strain gauge and the SOI silicon wafer substrate is realized.
Compared with the prior art, the application has the following beneficial effects:
the stress sensitive structure of the strain gauge is positioned in the center of the supporting frame, so that the stress sensitive structure can be effectively protected from damage; the support beams are arranged between the stress sensitive beams, so that the strength of the stress sensitive beams is enhanced, and the probability of stress sensitive resistor fracture can be reduced;
secondly, the pickup parts are arranged in the middle of the supporting structures at the left end and the right end, so that the area can be sucked in vacuum in later application, such as packaging, testing equipment and the like, to pick up the glass micro-melting pressure sensor, thereby realizing batch automatic and accurate chip loading and effectively ensuring the accuracy and consistency of the produced glass micro-melting pressure sensor; in addition, as the bonding pads of the metal electrodes are only arranged on the pick-up structure, the influence of stress among different materials on the piezoresistor can be reduced;
finally, a plurality of sensitive resistors are arranged on the stress sensitive beam, and the sensitive resistors are connected through at least two connecting wires, so that the stress sensitive beam can effectively fail due to the fact that the stress sensitive structure breaks, and the working reliability of the stress sensitive beam is improved.
Drawings
FIG. 1 is a schematic diagram of a conventional silicon strain gauge;
FIG. 2 is a schematic diagram of a silicon strain gauge of the present application;
FIG. 3 is a flow chart of a method of fabricating a silicon strain gauge of the present application;
FIG. 4 is a schematic structural diagram of an SOI silicon wafer;
FIG. 5 is a schematic diagram of a structure for fabricating a P-type potential layer on an SOI silicon wafer;
FIG. 6 is a schematic diagram of an N-type epitaxial layer fabricated on the structure of FIG. 5;
FIG. 7 is a schematic diagram of a structure for fabricating a sense resistor on the structure of FIG. 6;
FIG. 8 is a schematic diagram of a structure for fabricating a dielectric layer over the structure of FIG. 7;
FIG. 9 is a schematic illustration of a structure in which a lead hole has been etched into the structure of FIG. 8;
FIG. 10 is a schematic diagram of the structure of FIG. 9 in which metal connection lines and metal electrodes are fabricated;
FIG. 11 is a schematic diagram of a passivation layer fabricated on the structure of FIG. 10;
FIG. 12 is a schematic view of a structure in which a second lead hole is formed in the structure of FIG. 11;
FIG. 13 is a schematic illustration of the structure of FIG. 12 with stress sensitive and support beams etched thereon;
FIG. 14 is a schematic view of the structure of FIG. 13 with the substrate removed;
FIG. 15 is a schematic diagram of a sense resistor connection on a conventional silicon strain gauge;
FIG. 16 is a schematic diagram of the sensing resistor connection of a silicon strain gauge of the present application;
FIG. 17 is a schematic view of the present application secured to a stainless steel elastomer;
fig. 18 is a schematic view of stress sensitive beams, support beams, sensitive resistors and connecting wires on a single support frame in fig. 2.
Detailed Description
Illustrative embodiments of the application include, but are not limited to, a silicon strain gauge and method of manufacture.
Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The implementations described in the following exemplary examples do not represent all implementations consistent with the application. Rather, they are merely examples of apparatus and methods consistent with aspects of the application as detailed in the accompanying claims. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any or all possible combinations of one or more of the associated listed items. The word "comprising" or "comprises", and the like, means that elements or items appearing before "comprising" or "comprising" are encompassed by the element or item recited after "comprising" or "comprising" and equivalents thereof, and that other elements or items are not excluded. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. It should be understood that although the terms first, second, third, etc. may be used herein to describe various information, these information should not be limited by these terms. These terms are only used to distinguish one type of information from another. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information, without departing from the scope of the application. The term "if" as used herein may be interpreted as "at..once" or "when..once" or "in response to a determination", depending on the context.
As shown in fig. 2, a silicon strain gauge comprises a body 1, wherein a first supporting frame 2, a pick-up part and a second supporting frame 8 are sequentially arranged on the body 1 along the length direction of the body 1, the first supporting frame 2 and the second supporting frame 8 are symmetrically arranged about the pick-up part, a stress sensitive structure is arranged on the inner wall of each supporting frame, the stress sensitive structure comprises two parallel stress sensitive beams 3 fixed on the inner wall of the supporting frame, the length direction of each stress sensitive beam 3 is identical to the length direction of the body 2, and three supporting beams 4 are arranged between the two stress sensitive beams 3 on each supporting frame 2;
at least one sensitive resistor 5 is arranged on each stress sensitive beam 3 along the length direction of the stress sensitive beam 3, and the sensitive resistors 5 on the two stress sensitive beams 3 on each supporting frame 2 are connected through a connecting wire 6;
a metal electrode 7 for transmitting sensitive resistance signals is arranged on the body 1 between the two support frames 2.
In addition, in the present embodiment, a schematic diagram of the stress sensitive beam 3, the support beam 4, the sensitive resistor 5, and the connection line 6 on the single support frame 2 in fig. 2 is shown in fig. 18.
For the silicon strain gauge of the application, the two stress-sensitive beams 3 of the support frame 2 can ensure the strength of the stress-sensitive beams 3 due to the connection of the support beams 4, and in addition, in the embodiment, the size designs of the stress-sensitive beams 3 and the support beams 4 are the same. In practical use, by making the size designs of the stress sensitive beam 3 and the support beam 4 identical, the consistency of the slurry overflow height around the stress sensitive beam 3 can be ensured when the silicon strain gauge is sintered on the stainless steel elastomer 30.
In some embodiments, the number of the supporting beams 4 is not necessarily limited to three in fig. 2, and may be one, two or more than four, and the specific number may be set according to actual requirements. When the number of the stress sensitive beams 4 is M, M is a positive integer, and all the support beams 4 divide the stress sensitive beam 3 into m+1 segments of equal length.
Specifically, in this embodiment, the silicon strain gauge of the present application has a bilateral symmetry structure.
Specifically, in this embodiment, the sensing resistor 5 on the stress sensitive beam 3 forms a wheatstone bridge through the connecting wire 6, so that the conversion from the pressure signal to the electric signal can be realized, and the risk of breakage of the sensing resistor 5 can be reduced by disposing the sensing resistor 5 on the stress sensitive beam 3. In addition, the firmness of the application can be improved by arranging the body 1, and effective protection can be provided for the sensitive part of the application, wherein the sensitive part is in a structure in a broken line box at the leftmost side in fig. 2.
In actual use, if each resistor constituting the wheatstone bridge is a single resistor branch as shown in fig. 15, in actual use, if any resistor segment or junction breaks, the device will fail. As an improvement, in this embodiment, two parallel sensitive resistors 5 are provided on each stress sensitive beam 3; the sensitive resistors 5 on the two pressure sensitive beams 3 on each support frame 2 are electrically connected through at least two connecting wires 6; a schematic diagram of the connection of the sense resistors 5 on two stress sensitive beams 3 can be seen with reference to fig. 16. In practical use, by the application, even if one sensitive resistor 5 cannot be used or one connecting wire 6 breaks, the rest sensitive resistor 5 and the connecting wire 6 form a resistor path.
Specifically, in fig. 2, the sensitive resistors 5 on the two stress sensitive beams 3 are electrically connected by three connection lines 6, two connection lines 6 of the three connection lines 6 are provided on the two support beams 4, and one connection line 6 is provided on the body 1. In some embodiments, the number and arrangement positions of the connecting wires 6 can be adjusted according to actual requirements.
In fig. 2, the metal electrode 7 includes a first metal electrode 70, a second metal electrode 71 and a third metal electrode 72, wherein the two stress sensitive beams 3 on the first support frame 2 and the second support frame 8 are used as front stress sensitive beams and rear stress sensitive beams, the first metal electrode 70 is electrically connected with the sensitive resistors 5 on the two front stress sensitive beams, the second metal electrode 71 is electrically connected with the sensitive resistors 5 on the rear stress sensitive beams on the first support frame 2, and the third metal electrode 72 is electrically connected with the sensitive resistors 5 on the rear stress sensitive beams on the second support frame 8.
In some embodiments, the shapes and arrangement positions of the first metal electrode 70, the second metal electrode 71, and the third metal electrode 72 may be adjusted according to actual requirements.
Specifically, in fig. 2, the sense resistor 5 in the stress sensitive structure in the first support frame 2 and the connection line 6 thereof constitute a stress sensitive resistor R1 in the wheatstone half bridge as in fig. 16, and the sense resistor 5 in the stress sensitive structure in the second support frame 8 and the connection line 6 thereof constitute a stress sensitive resistor R2 in the wheatstone half bridge as in fig. 16. As shown in fig. 16, both ends of the first metal electrode 70 are electrically connected to the stress sensitive resistor R1 and the stress sensitive resistor R2, respectively, as output ends of the wheatstone bridge; the second metal electrode 71 is connected with the other end of the stress sensitive resistor R1 and is used as a power end of the Wheatstone bridge; the third metal electrode 72 is connected to the other end of the stress sensitive resistor R2 and serves as a wheatstone power bridge ground. Of course, in practical application, the power supply end may be the third metal electrode 72, and the ground end is the second metal electrode 71.
Specifically, in this embodiment, the present application further includes a stainless steel elastic body 30, and the body 1 is fixed to the stainless steel elastic body 30 by a sintered slurry layer 31, wherein a schematic structural view of the body 1 fixed to the stainless steel elastic body 30 is shown in fig. 17. The silicon strain gauge is sintered on the stainless steel elastomer through glass slurry at high temperature, and for the existing silicon strain gauge, as the body 1 is not arranged, the overflow height of the glass slurry is influenced by the material characteristics and the physical structure of the stainless steel elastomer 30 and the silicon strain gauge, so that the periphery of the silicon strain gauge is different from the overflow height of the silicon strain gauge. For the silicon strain gauge, due to the arrangement of the body 1, the consistency of overflow of glass slurry on the periphery of the stress sensitive beam 3 can be ensured through the body 1, so that the balance of internal stress of the stress sensitive beam after sintering can be realized, and the stability and the reliability of the glass micro-melting pressure sensor are ensured.
In summary, the silicon strain gauge of the present application firstly sets two parallel stress sensitive beams 3 on the support frame 2 and sets the support beam 4 between the two stress sensitive beams 3, so as to ensure the strength of the stress sensitive beams 3, and sets the sensitive resistor 5 on the stress sensitive beams 3, so as to form a wheatstone bridge for converting the pressure signal into the electric signal, and by setting the sensitive resistor 5 on the stress sensitive beams 4, the fracture probability of the sensitive resistor 5 can be reduced;
secondly, the two support frames 2 are arranged at intervals, so that the pick-up equipment can pick up the glass micro-melting pressure sensor in the area between the two support frames 2, automatic and accurate chip loading in batches can be realized, and the accuracy and consistency of the produced glass micro-melting pressure sensor are effectively ensured; in addition, as the metal electrode 7 is only arranged between the two support frames 2, the influence of stress among different materials on the piezoresistor 5 can be reduced;
finally, by arranging two sensitive resistors 5 on the stress sensitive beam 3 and connecting the two sensitive resistors 5 through at least two connecting wires 6, the application can effectively avoid failure caused by fracture of the sensitive resistors 5, thereby improving the working reliability of the application.
In a second aspect, as shown in fig. 3, the present application further provides a method for manufacturing a silicon strain gauge, including the steps of:
s1: the P-type potential layer 11 is fabricated by implanting ions into the top surface of the SOI silicon wafer 10 by ion implantation techniques.
The structure of the SOI wafer 10 is shown in fig. 4, and includes a substrate 100, a buried oxide layer 101, and a top silicon layer 102, which are stacked in this order from bottom to top. Wherein the resistivity of the SOI silicon wafer 10 is 1-10 ohm.cm, the thickness of the top silicon 102 is 1-2 mu m, and the thickness of the middle buried oxide layer 101 is 0.2-1.0 mu m.
Specifically, the P-type potential layer 11 is formed by implanting boron ions into the top surface of the SOI silicon wafer 10 and then annealing the SOI silicon wafer in step S1. The structure of the P-type potential layer 11 fabricated on the top surface of the SOI wafer 10 is shown in fig. 5.
S2: an N-type epitaxial layer 12 is formed on the top surface of the P-type potential layer 11 by an epitaxial technique.
The schematic diagram of the N-type epitaxial layer 12 fabricated on the top surface of the P-type potential layer 11 is shown in fig. 6, the thickness of the N-type epitaxial layer 12 is the thickness of the silicon strain gauge, the thickness of the N-type epitaxial layer 12 is between 20um and 50um, and the N-type epitaxial layer 12 and the P-type potential layer 11 form the body 1.
S3: the sensing resistor 5 is fabricated by ion implantation on the top surface of the N-type epitaxial layer 12.
Since a plurality of silicon strain gauges are simultaneously manufactured on the SOI wafer 10 at the time of manufacturing the silicon strain gauge, step S3 is to manufacture the sense resistor 5 for each silicon strain gauge on the SOI wafer 10. Taking the example of manufacturing the sensitive resistor 5 on a silicon strain gauge, two groups of sensitive resistors 5 are manufactured by implanting ions on the top surface of the N-type epitaxial layer 12 through an ion implantation technology, and each group of sensitive resistors 5 comprises a front sensitive resistor and a rear sensitive resistor which are parallel, and the two groups of sensitive resistors are arranged at a left-right interval. Specifically, in step S3, boron ions are implanted into the top surface of the N-type epitaxial layer 12, and then the device is annealed to produce two sets of sensitive resistors 5, and the schematic structure of the produced sensitive resistors 5 is shown in fig. 7.
Specifically, each group of sensitive resistors 5 in step S3 includes two front sensitive resistors and two rear sensitive resistors, the two front sensitive resistors are arranged in parallel, the two rear sensitive resistors are arranged in parallel, and the metal connecting wire 15 manufactured in step S6 is electrically connected with the two front sensitive resistors and the two rear sensitive resistors, respectively. Taking the stress sensitive structure on the left side of fig. 2 as an example, the upper sensitive resistor 5 is a front sensitive resistor, and the lower sensitive resistor 5 is a rear sensitive resistor.
S4: manufacturing a dielectric layer 13 covering the sensitive resistor 5 on the N-type epitaxial layer 12 by a vapor deposition technology; a schematic structure of the completed dielectric layer 13 is shown in fig. 8.
Specifically, the dielectric layer 13 may be made by an LPCVD technique; wherein the dielectric layer 13 is SiO 2 And SiNx, siO 2 The thickness of the film is between 0.2um and 0.3 um; the thickness of SiNx is between 0.1um and 0.15 um.
S5: a lead hole 14 for leading out the sensitive resistor 5 is etched in the dielectric layer 13 by etching technology, and a schematic diagram of the etched lead hole 14 is shown in fig. 9.
S6: sputtering metal on the dielectric layer 13 to form a metal layer, performing photoetching, etching or corrosion on the metal layer to form metal connecting wires 15 between the sensitive resistors 5 and metal electrodes 7 for packaging or testing.
The sense resistors 5 refer to a front sense resistor and a rear sense resistor in each group of sense resistors 5.
Wherein a plurality of metal connection lines 15 may be made to electrically connect the front and rear sensitive resistors.
Specifically, the thickness of the metal layer is between 1um and 2 um; the metal layer can be made of AL, au or Pt.
S7: growing a passivation layer 16 on the dielectric layer 13 by a vapor deposition technology, wherein the passivation layer 16 covers the metal connecting wire 15 and the metal electrode 7; the structure of the grown passivation layer 16 is shown in fig. 11.
Specifically, PEVCD techniques may be used to grow passivation layer 16, wherein the material of the passivation layer is SiO 2 The thickness of the passivation layer is between 0.4um and 0.6 um; or the passivation layer is made of SiNx, and the thickness of the passivation layer is between 0.2um and 0.3 um.
S8: a pad region of the metal electrode is etched and etched on the passivation layer 16.
Specifically, step S8 is for etching out the second lead hole 17 extending to the metal electrode 7.
S9: the support structure 21 and the stress sensitive structure 20 are etched on the device after step S8 is performed, while scribe grooves between the individual silicon strain gauges on the SOI wafer are etched away. Wherein the support structure 21 is the body 1.
Specifically, the front stress sensitive beam of the front sensitive resistor and the rear stress sensitive beam of the rear sensitive resistor can be etched through step S9, and at least one support beam 6 connecting the front stress sensitive beam and the rear stress sensitive beam can be etched.
Specifically, in step S9, the stress sensitive beam and the support beam 6 are etched by the MEMS deep silicon etching process, and the stop layer of this etching is the buried oxide layer 101 of the SOI silicon wafer 10. I.e. the stress-sensitive structure 20 and the support structure 21 of the silicon strain gauge can be etched out by means of step S9.
In actual fabrication, there are chip units on the SOI wafer 10, and scribe areas between the chip units may be etched in step S9.
S10: the buried oxide layer 101 of the SOI silicon wafer 10 is removed by adopting a gaseous HF release process, so that each silicon strain gauge on the SOI silicon wafer 10 is separated from the substrate 100 of the SOI silicon wafer 10, and the separated silicon strain gauge is obtained.
Specifically, in step S10, the buried oxide layer 101 of the SOI wafer 10 is removed by a gaseous hydrogen fluoride etching process, thereby separating the silicon strain gauge from the substrate 100.
In addition, it should be noted that only the sensitive resistor 5 on one support frame is shown in fig. 4 to 14, but since the structure of the silicon strain gauge is left-right symmetric, the person skilled in the art can know the schematic structure of the whole silicon strain gauge.
The present application has been made in view of the above-described circumstances, and it is an object of the present application to provide a portable electronic device capable of performing various changes and modifications without departing from the scope of the technical spirit of the present application. The technical scope of the present application is not limited to the description, but must be determined according to the scope of claims.
Claims (10)
1. The silicon strain gauge is characterized by comprising a body, wherein a first supporting frame, a pick-up part and a second supporting frame are sequentially arranged on the body along the length direction of the body, the first supporting frame and the second supporting frame are supporting structures, stress sensitive structures are arranged on the first supporting frame and the second supporting frame, each stress sensitive structure comprises two parallel stress sensitive beams fixed on the inner wall of the supporting frame, the length direction of each stress sensitive beam is identical to the length direction of the body, M supporting beams are arranged between the two stress sensitive beams on each supporting frame, and M is a positive integer;
at least one sensitive resistor is arranged on each stress sensitive beam along the length direction of the stress sensitive beam, and the sensitive resistors on the two stress sensitive beams on each supporting frame are connected through a connecting wire;
the pick-up part is provided with a metal electrode for transmitting sensitive resistance signals.
2. A silicon strain gauge according to claim 1, wherein each stress sensitive beam is provided with two parallel sensitive resistors;
the sensitive resistors on the two pressure sensitive beams on each support frame are electrically connected through at least two connecting wires.
3. A silicon strain gauge as claimed in claim 1 wherein M is a positive integer greater than 1, and wherein all support beams divide the stress sensitive beam into equally spaced m+1 sections.
4. The silicon strain gauge of claim 1, wherein the metal electrodes comprise a first metal electrode, a second metal electrode and a third metal electrode, wherein the two stress sensitive beams on the support frame are used as front stress sensitive beams and rear stress sensitive beams, the first metal electrode is electrically connected with the sensitive resistors on the two front stress sensitive beams, the second metal electrode is electrically connected with the sensitive resistor on one rear stress sensitive beam, and the third metal electrode is electrically connected with the sensitive resistor on the other rear stress sensitive beam.
5. The silicon strain gauge of any of claims 1-4 further comprising a stainless steel elastomer, the body being secured to the stainless steel elastomer by a sintered slurry layer.
6. A method of manufacturing a silicon strain gauge for producing a silicon strain gauge as claimed in any one of claims 1 to 5, comprising the steps of:
s1: implanting ions into the top surface of the SOI silicon wafer by an ion implantation technology to manufacture a P-type potential layer;
s2: manufacturing an N-type epitaxial layer on the top surface of the P-type potential layer through an epitaxial technology;
s3: ion implantation technology is used for implanting ions on the top surface of the N-type epitaxial layer to manufacture a sensitive resistor;
s4: manufacturing a dielectric layer covering the sensitive resistor on the N-type epitaxial layer by a vapor deposition technology;
s5: etching a lead hole for leading out the sensitive resistor on the dielectric layer by an etching technology;
s6: sputtering metal on the dielectric layer to form a metal layer, and carrying out photoetching, etching or corrosion on the metal layer to form a metal connecting wire between sensitive resistors and a metal electrode for packaging or testing;
s7: growing a passivation layer on the dielectric layer by a vapor deposition technology, wherein the passivation layer covers the metal connecting wire and the metal electrode;
s8: photoetching and etching a bonding pad area of the metal electrode on the passivation layer;
s9: etching a supporting structure and a stress sensitive structure on the device after the step S8 is executed, and etching scribing grooves among all silicon strain gauges on the SOI silicon wafer;
s10: and removing the buried oxide layer of the SOI silicon wafer by a gaseous hydrogen fluoride etching process, so as to realize separation of the silicon strain gauge and the SOI silicon wafer.
7. The method of manufacturing a silicon strain gauge according to claim 6, wherein in step S1, the P-type potential layer is formed by implanting boron ions into the top surface of the SOI wafer and then annealing the SOI wafer; in step S3, two sets of sensitive resistors are fabricated by implanting boron ions on the top surface of the N-type epitaxial layer and then annealing the device.
8. The method of manufacturing a silicon strain gauge according to claim 6, wherein the dielectric layer is made of SiO2 and SiNx, and the thickness of SiO2 is between 0.2um and 0.3 um; the thickness of the SiNx is between 0.1um and 0.15 um;
the material of the passivation layer is SiO2, and the thickness of the passivation layer is between 0.4um and 0.6 um; or the passivation layer is made of SiNx, and the thickness of the passivation layer is between 0.2um and 0.3 um.
9. The method of manufacturing a silicon strain gauge according to claim 6, wherein the sensing resistors in the step S3 include two front sensing resistors and two rear sensing resistors, the two front sensing resistors are arranged in parallel, the two rear sensing resistors are arranged in parallel, and the metal connecting wires manufactured in the step S6 are electrically connected with the two front sensing resistors and the two rear sensing resistors, respectively.
10. The method of manufacturing a silicon strain gauge according to claim 6, wherein in step S9, the support structure and the stress sensitive structure are etched by a MEMS deep silicon etching process, and the stop layer of the etching is an oxygen buried layer of the SOI silicon wafer.
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