CN220153640U - Gas flow sensor chip with high sensitivity - Google Patents
Gas flow sensor chip with high sensitivity Download PDFInfo
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- CN220153640U CN220153640U CN202321275907.XU CN202321275907U CN220153640U CN 220153640 U CN220153640 U CN 220153640U CN 202321275907 U CN202321275907 U CN 202321275907U CN 220153640 U CN220153640 U CN 220153640U
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- 239000002184 metal Substances 0.000 claims abstract description 29
- 229910052751 metal Inorganic materials 0.000 claims abstract description 29
- 238000010438 heat treatment Methods 0.000 claims abstract description 26
- 239000012530 fluid Substances 0.000 claims abstract description 19
- 230000001681 protective effect Effects 0.000 claims abstract description 16
- 238000009529 body temperature measurement Methods 0.000 claims abstract description 13
- 239000010410 layer Substances 0.000 claims description 53
- 238000000034 method Methods 0.000 claims description 26
- 230000008569 process Effects 0.000 claims description 25
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 16
- 238000011144 upstream manufacturing Methods 0.000 claims description 16
- 239000000463 material Substances 0.000 claims description 13
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 8
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- 239000000377 silicon dioxide Substances 0.000 claims description 8
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 8
- 238000005019 vapor deposition process Methods 0.000 claims description 6
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- 229910052804 chromium Inorganic materials 0.000 claims description 2
- 229910052802 copper Inorganic materials 0.000 claims description 2
- 239000000725 suspension Substances 0.000 abstract description 5
- 238000013461 design Methods 0.000 abstract description 3
- 238000005530 etching Methods 0.000 description 9
- 238000004519 manufacturing process Methods 0.000 description 9
- 238000009413 insulation Methods 0.000 description 6
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- 238000001514 detection method Methods 0.000 description 4
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 229910052737 gold Inorganic materials 0.000 description 3
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- IGELFKKMDLGCJO-UHFFFAOYSA-N xenon difluoride Chemical compound F[Xe]F IGELFKKMDLGCJO-UHFFFAOYSA-N 0.000 description 1
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Abstract
The utility model relates to a gas flow sensor chip with high sensitivity, which comprises a substrate, a support film, a metal film and a protective film which are sequentially arranged from bottom to top; the upper surface of the substrate is provided with a cavity which forms a flow channel along the fluid direction; the support film is patterned, and the patterned opening is positioned above the cavity area, so that the cavity is communicated with the outside; the metal film is patterned and comprises at least one heating pattern, at least two temperature measurement patterns and at least one calibration pattern; the protective film is positioned at the uppermost part and is used for protecting the metal film from being in direct contact with the fluid; the utility model designs the cavity as a complete flow channel along the fluid direction, so that the heating resistor and the temperature measuring resistor span the whole cavity, the upper and lower parts of the sensor suspension film are contacted with the fluid, the heat exchange quantity of the fluid, the sensor heating resistor and the temperature measuring resistor is greatly improved, and the sensor can obtain a larger output signal at a smaller flow rate.
Description
Technical Field
The utility model relates to the field of micro-electromechanical body flow sensors, in particular to a gas flow sensor chip with high sensitivity.
Background
The detection of gas flow is indispensable in many systems and devices. With the development of microelectromechanical (MEMS) technology, MEMS-based gas flow sensors are becoming popular and widely used in various industrial, commercial and medical applications, wherein thermal gas flow sensors have received attention because of their advantages of simple structure, low manufacturing cost and easy miniaturization.
The thermal gas flow sensor is based on the principle of heat transfer, and uses the gas flow to prevent the upstream and downstream temperatures from being used, and the gas flow is obtained by detecting the upstream and downstream temperature differences. The temperature measuring mode of the thermal type gas flow sensor mainly comprises two types, namely a thermopile type, wherein the thermopile type is based on the Seebeck effect, the same thermopiles are arranged at the upper and lower sides respectively, potential difference signals are generated when the temperature difference exists at the upper and lower sides, the temperature difference between the upper and lower sides can be obtained through measuring the potential difference, the same resistor exists at the upper and lower sides, the resistance values are different when the temperature difference exists at the upper and lower sides, and the difference of the resistors can be detected through a circuit, so that the temperature difference is known. The thermopile type gas flow sensor has the advantages of no need of external bias voltage, mature process and good stability, but has relatively poorer sensitivity compared with the thermal resistance type gas flow sensor.
The gas flow sensor and the manufacturing method thereof disclosed in the prior art CN104280085A avoid heat loss caused by film heat conduction by separating a heating resistor and a temperature measuring resistor, greatly improve the detection sensitivity of the MEMS thermal conductivity gas flow sensor and have the advantage of simple process; however, the idea is to reduce the heat loss of the heating resistor, and the heat convection between the heating resistor and the temperature measuring resistor caused by the gas flow is not increased, so that the sensitivity of the sensor is limited.
In addition, as disclosed in CN214748202U in the prior art, the suspension membrane is made of two layers of different materials, after the cavity is released, the suspension membrane forms an upward bending shape under the action of the pressure stress of the membrane, compared with a planar suspension membrane, the bending membrane has a larger surface area, and the upstream flow velocity is accelerated while the downstream flow buffer area is formed, so that the heat exchange efficiency of the fluid and the surface of the sensor is improved, and the gas flow detection sensitivity is improved; however, the bending suspension film related to the technology is realized through the stress of the film, the bending degree of the film is larger when the stress is large, and meanwhile, the risk of film breakage is larger, so that the requirement of not only obtaining the larger bending degree and improving the sensitivity is higher, but also ensuring that the film is stable and cannot be broken is needed, the control requirement on the film stress in the process is more severe, and the difficulty of the process is larger than that of other films.
Disclosure of Invention
The utility model aims to overcome the defects of the prior art and provide a gas flow sensor chip with high sensitivity, so that a sensor can obtain a larger output signal at a smaller flow rate.
In order to achieve the above purpose, the utility model adopts the following technical scheme: a gas flow sensor chip with high sensitivity and a manufacturing method thereof, comprising a substrate, a support film, a metal film and a protective film which are arranged in sequence from bottom to top;
the upper surface of the substrate is provided with a cavity which forms a flow channel along the fluid direction, and the depth of the cavity does not exceed the thickness of the substrate;
the support film is patterned, and the patterned opening is positioned above the cavity area, so that the cavity is communicated with the outside;
the metal film is patterned and comprises at least one heating pattern, at least two temperature measurement patterns and at least one calibration pattern; the heating pattern is positioned at the center of the cavity, and the pattern is symmetrical about a center point; the temperature measurement pattern is positioned above the cavity and comprises at least one upstream temperature measurement pattern and at least one downstream temperature measurement pattern; the upstream temperature measurement pattern is identical to the downstream temperature measurement pattern and is symmetrical with respect to the intermediate heating pattern; the calibration pattern is positioned at the position without a cavity at the edge of the substrate;
the protective film is positioned at the uppermost for protecting the metal film from direct contact with the fluid.
Preferably, the support film has a single-layer structure or a composite structure, and the material layer is one or more of insulating layers such as silicon dioxide, silicon nitride and the like.
Preferably, the thickness of the supporting film layer is 5000A-20000A, and the supporting film layer is prepared by adopting a plasma vapor deposition process or a thermal oxidation process.
Preferably, the metal film comprises an adhesion layer and a thermosensitive layer, wherein the adhesion layer is made of one of Ti and Cr, and the thermosensitive layer is made of one of Pt, ni and Cu, and the resistivity of the thermosensitive layer is sensitive to temperature change.
Preferably, the thickness of the metal film layer is between 1000A and 10000A, and the metal film layer is prepared by adopting a physical vapor deposition process.
Preferably, the protective film is positioned at the uppermost part, the patterned opening is consistent with the support film, and the material is a composite film containing silicon dioxide and silicon nitride.
Preferably, the thickness of the protective film layer is 5000-15000A, and the protective film is prepared by adopting a plasma vapor deposition process.
Due to the application of the technical scheme, compared with the prior art, the utility model has the following advantages:
the utility model informs that the cavity is designed as a complete flow channel along the fluid direction, at the moment, the heating resistor and the temperature measuring resistor are positioned on the supporting film and span the whole heat insulation cavity, the upper and lower parts of the sensor suspended film are contacted with the fluid, and the design greatly improves the heat exchange quantity of the fluid, the heating resistor of the sensor and the temperature measuring resistor from the perspective of promoting the heat exchange between the fluid and the surface of the sensor, so that the sensor can obtain larger output signals at smaller flow rate, the sensitivity of the gas flow sensor is greatly improved, and the structure has the advantages of simple process, low cost, low power consumption and the like.
Drawings
The technical scheme of the utility model is further described below with reference to the accompanying drawings:
FIG. 1 is a schematic diagram of a gas flow sensor chip with high sensitivity according to the present utility model;
FIG. 2 is a cross-sectional view of a gas flow sensor chip with high sensitivity in the yz plane according to the present utility model;
FIG. 3 is a cross-sectional view of a gas flow sensor chip with high sensitivity in the xz plane according to the present utility model;
fig. 4 is a flow chart of the fabrication of a gas flow sensor chip with high sensitivity according to the present utility model.
Wherein: 1. a substrate; 2. a cavity; 3. an upstream temperature measuring resistor; 4. heating the resistor pattern; 5. a downstream temperature measuring resistor; 6. calibrating the resistor pattern; 7. a support film; 8. and a protective film.
Description of the embodiments
The utility model will be described in further detail with reference to the accompanying drawings and specific examples.
Fig. 1-3 are diagrams showing a gas flow sensor chip with high sensitivity according to the present utility model, comprising a substrate 1, a support film 7, a metal film, and a protective film 8; the substrate 1 is positioned at the lowest part, and a supporting film 7, a metal film and a protective film 8 are sequentially arranged on the upper layer;
the substrate 1 is provided with a cavity 2, the cavity 2 is positioned on the upper surface of the substrate 1, the substrate 1 is recessed downwards for a certain distance to form the cavity 2, the whole metal film area is covered by the cavity 2 area, a flow channel is formed along the fluid direction, and the depth of the cavity 2 is not more than the thickness of the substrate 1; wherein the material of the substrate 1 can be monocrystalline silicon, polycrystalline silicon, SOI silicon wafer and the like, and in the embodiment, the material of the substrate 1 is monocrystalline silicon;
the support film 7 is patterned, and a patterned opening is positioned above the area of the cavity 2, so that the cavity 2 is communicated with the outside; the supporting film 7 has a single-layer structure or a composite structure, and the material layer is one or more of insulating layers such as silicon dioxide, silicon nitride and the like;
the metal film is patterned and comprises at least one heating resistor pattern 4, at least two temperature measuring resistor patterns and at least one calibration resistor pattern 6; the heating resistor pattern 4 is positioned at the center of the cavity 2, and the pattern is symmetrical about a center point; the temperature measuring resistor pattern is positioned above the cavity 2 and comprises at least one upstream temperature measuring resistor 3 and at least one downstream temperature measuring resistor 5, wherein the upstream temperature measuring resistor 3 is identical to the downstream temperature measuring resistor 5 and is symmetrical with respect to the intermediate heating resistor pattern 4; the calibration resistor pattern 6 is positioned at the position without the cavity 2 at the edge of the substrate 1; the metal layer comprises an adhesion layer and a thermosensitive layer, the adhesion layer is made of one of Ti, cr and the like, and the thermosensitive layer is made of a material with resistivity very sensitive to temperature change, such as Pt, ni, cu and the like;
the protective film 8 is positioned at the uppermost part, the patterned opening is consistent with the support film 7, and the material is a composite film containing silicon dioxide and silicon nitride.
The gas flow sensor in the present embodiment is a thermal type gas flow sensor that obtains information of gas flow by detecting a change in thermal resistance; when the flow rate of the external gas is 0, the heat exchange between the sensor and the external gas is 0, the thermal field distribution of the sensor is in a stable state, the middle heating resistor works at a certain fixed temperature, the temperature difference of the upstream and downstream heating resistors is 0 because the temperature measuring resistor patterns are identical and symmetrical with respect to the middle heating resistor patterns, the output voltage signal of the Wheatstone bridge formed by the upstream and downstream heating resistors is also 0, when the flow rate of the external gas is not 0, the heat of the upstream resistor is transferred to the downstream resistor through the heat convection between the gas and the surface of the sensor, the upstream temperature is lower than the downstream temperature, the temperature difference is formed, the temperature difference is related to the flow rate, and the output voltage signal of the Wheatstone bridge formed by the upstream and downstream heating resistors is not 0.
In the flow sensor structure shown in fig. 1, the heating resistor and the substrate are separated by the heat insulation cavity, so that heat loss through the substrate is avoided, in addition, referring to the design in patent CN214748202U, the supporting film and the protecting film are patterned, so that the heating resistor and the upstream and downstream temperature measuring resistor are not located on the continuous film, and the detection sensitivity is improved; in addition, the sensitivity of the sensor chip is improved by increasing the heat exchange between the fluid and the sensitive resistor, as shown in fig. 1, the heat insulation cavity is designed to form a complete flow channel along the fluid direction, the heating resistor and the temperature measuring resistor are positioned on the supporting film, cross the whole heat insulation cavity, and the cross section of the heat insulation cavity along the fluid flow direction is shown in fig. 2.
Fig. 4 is a schematic diagram of a method for manufacturing a gas flow sensor chip according to the present utility model, which specifically includes the following process flows:
step S01, providing a semiconductor substrate, wherein the substrate material can be monocrystalline silicon, polycrystalline silicon, SOI silicon wafer and the like; manufacturing a supporting layer on the substrate, wherein the supporting film layer is of a single-layer structure or a composite structure, and the contained material layer is one or more of a silicon dioxide layer, a silicon nitride layer and the like; the thickness of the supporting film layer is 5000A-20000A, and the supporting film layer is prepared by adopting a plasma vapor deposition process, a low-pressure chemical vapor deposition process, a thermal oxidation process and the like; the support film has better mechanical property and insulating property, is used for supporting the metal film pattern on one hand, and also provides electric isolation between the substrate and the metal film on the other hand;
step S02, manufacturing a metal layer on the supporting layer and patterning; the metal layer comprises an adhesion layer and a thermosensitive layer, the adhesion layer is made of one of Ti, cr and the like, and the thermosensitive layer is made of a material with resistivity very sensitive to temperature change, such as Pt, ni, cu and the like; the patterning process can be etching or stripping process after photoetching patterning;
step S03, manufacturing a protective layer on the metal layer; the protective layer comprises a composite film of silicon dioxide and silicon nitride, and is prepared by adopting a plasma vapor deposition process, and the thickness of the film layer is 5000-15000A; the protective layer is used for protecting the metal film part of the chip from being in direct contact with the outside or fluid during working;
step S04, etching and windowing the protective layer; the etching windowing process is a reactive ion etching process, an ion beam etching process and the like;
step S05, manufacturing a metal electrode at the window of the protective layer and patterning; the metal material can be Ti/Au, cr/Au, ti/Al, cr/Al and the like, and comprises an adhesion layer Ti, cr and the like and a metal layer Au, al and the like; the metal electrode is prepared by adopting a physical vapor deposition process, and the thickness of the film layer is between 1000A and 10000A; the patterning process can be etching or stripping process after photoetching patterning;
step S06, etching and windowing the protective layer and the supporting layer, wherein the front surface is exposed out of the substrate; the etching windowing process is a reactive ion etching process, an ion beam etching process and the like;
step S07, corroding the semiconductor substrate to form a heat insulation cavity; the substrate etching may be a wet etching or a dry etching process; in this embodiment, the substrate is monocrystalline silicon, and the silicon substrate may be anisotropically etched with KOH, or a XeF2 gas dry etching process may be used.
The foregoing is merely a specific application example of the present utility model, and the protection scope of the present utility model is not limited in any way. All technical schemes formed by equivalent transformation or equivalent substitution fall within the protection scope of the utility model.
Claims (7)
1. A gas flow sensor chip with high sensitivity, characterized in that: comprises a substrate, a supporting film, a metal film and a protective film which are sequentially arranged from bottom to top;
the upper surface of the substrate is provided with a cavity which forms a flow channel along the fluid direction, and the depth of the cavity does not exceed the thickness of the substrate;
the support film is patterned, and the patterned opening is positioned above the cavity area, so that the cavity is communicated with the outside;
the metal film is patterned and comprises at least one heating pattern, at least two temperature measurement patterns and at least one calibration pattern; the heating pattern is positioned at the center of the cavity, and the pattern is symmetrical about a center point; the temperature measurement pattern is positioned above the cavity and comprises at least one upstream temperature measurement pattern and at least one downstream temperature measurement pattern; the upstream temperature measurement pattern is identical to the downstream temperature measurement pattern and is symmetrical with respect to the intermediate heating pattern; the calibration pattern is positioned at the position without a cavity at the edge of the substrate;
the protective film is positioned at the uppermost for protecting the metal film from direct contact with the fluid.
2. The gas flow sensor chip with high sensitivity according to claim 1, wherein: the support film is of a single-layer structure or a composite structure, and the material layer is one or more of silicon dioxide and silicon nitride insulating layers.
3. The gas flow sensor chip with high sensitivity according to claim 2, wherein: the thickness of the supporting film layer is 5000A-20000A, and the supporting film layer is prepared by adopting a plasma vapor deposition process or a thermal oxidation process.
4. A gas flow sensor chip with high sensitivity according to any one of claims 1-3, characterized in that: the metal film comprises an adhesion layer and a thermosensitive layer, wherein the adhesion layer is made of one of Ti and Cr, and the thermosensitive layer is made of one of Pt, ni and Cu, and the resistivity of the thermosensitive layer is sensitive to temperature change.
5. The gas flow sensor chip with high sensitivity according to claim 4, wherein: the thickness of the metal film layer is between 1000A and 10000A, and the metal film layer is prepared by adopting a physical vapor deposition process.
6. A gas flow sensor chip with high sensitivity according to any one of claims 1-3, characterized in that: the protective film is positioned at the uppermost part, the patterned opening is consistent with the support film, and the material is a composite film containing silicon dioxide and silicon nitride.
7. The gas flow sensor chip with high sensitivity according to claim 6, wherein: the thickness of the protective film layer is 5000-15000A, and the protective film is prepared by adopting a plasma vapor deposition process.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321275907.XU CN220153640U (en) | 2023-05-24 | 2023-05-24 | Gas flow sensor chip with high sensitivity |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321275907.XU CN220153640U (en) | 2023-05-24 | 2023-05-24 | Gas flow sensor chip with high sensitivity |
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| Publication Number | Publication Date |
|---|---|
| CN220153640U true CN220153640U (en) | 2023-12-08 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202321275907.XU Active CN220153640U (en) | 2023-05-24 | 2023-05-24 | Gas flow sensor chip with high sensitivity |
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| Country | Link |
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| CN (1) | CN220153640U (en) |
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2023
- 2023-05-24 CN CN202321275907.XU patent/CN220153640U/en active Active
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