CN111239224A - Gas sensor and preparation method thereof - Google Patents
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- CN111239224A CN111239224A CN202010138796.2A CN202010138796A CN111239224A CN 111239224 A CN111239224 A CN 111239224A CN 202010138796 A CN202010138796 A CN 202010138796A CN 111239224 A CN111239224 A CN 111239224A
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- 238000002360 preparation method Methods 0.000 title abstract description 7
- 239000000758 substrate Substances 0.000 claims abstract description 38
- 238000002161 passivation Methods 0.000 claims abstract description 22
- 239000004065 semiconductor Substances 0.000 claims abstract description 5
- 239000007789 gas Substances 0.000 claims description 221
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 27
- 229910002704 AlGaN Inorganic materials 0.000 claims description 24
- 230000004888 barrier function Effects 0.000 claims description 24
- MRELNEQAGSRDBK-UHFFFAOYSA-N lanthanum(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[La+3].[La+3] MRELNEQAGSRDBK-UHFFFAOYSA-N 0.000 claims description 19
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 claims description 19
- 239000000463 material Substances 0.000 claims description 16
- 238000004519 manufacturing process Methods 0.000 claims description 15
- 238000002955 isolation Methods 0.000 claims description 14
- 229910052697 platinum Inorganic materials 0.000 claims description 9
- 239000012528 membrane Substances 0.000 claims description 4
- 238000005530 etching Methods 0.000 claims description 3
- 239000010410 layer Substances 0.000 description 108
- 230000008859 change Effects 0.000 description 15
- 238000006243 chemical reaction Methods 0.000 description 9
- 238000000034 method Methods 0.000 description 7
- 238000010586 diagram Methods 0.000 description 5
- 239000002346 layers by function Substances 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 4
- 238000012423 maintenance Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000005538 encapsulation Methods 0.000 description 3
- 230000010354 integration Effects 0.000 description 3
- 230000005533 two-dimensional electron gas Effects 0.000 description 3
- -1 H can be tested2 Inorganic materials 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 230000036632 reaction speed Effects 0.000 description 2
- 229910052594 sapphire Inorganic materials 0.000 description 2
- 239000010980 sapphire Substances 0.000 description 2
- 238000000137 annealing Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000005468 ion implantation Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000001465 metallisation Methods 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000000059 patterning Methods 0.000 description 1
- 238000001020 plasma etching Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000008707 rearrangement Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/414—Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS
- G01N27/4141—Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS specially adapted for gases
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Abstract
The embodiment of the invention discloses a gas sensor and a preparation method thereof, wherein the gas sensor comprises: a substrate; the gas sensing units are positioned on the semiconductor substrate and comprise heterojunctions, source electrodes and drain electrodes positioned on the heterojunctions and grids formed by functional film layers, wherein the heterojunctions between the gas sensing units are mutually isolated, the functional film layers are used for detecting gas, the gas which can be detected by the functional film layers in different gas sensing units is different, and the passivation layer covers all device areas except the functional film layers, so that the gas sensors with different functions are integrated, and the cost is reduced.
Description
Technical Field
The embodiment of the invention relates to the technical field of gas sensors, in particular to a gas sensor and a preparation method thereof.
Background
Many types of gas sensors are used in gas detection systems. The sensors are divided into different sensors according to different applicable test conditions, such as test voltage, test current and the like.
Generally, the design of gas sensors for different purposes is a single package design. This allows a plurality of gas sensors with different functions to be obtained, but such a separate design package would increase the maintenance cost of the detection system.
Disclosure of Invention
The invention provides a gas sensor and a preparation method thereof, which are used for integrating a plurality of gas sensors with different functions and reducing the cost.
In a first aspect, an embodiment of the present invention provides a gas sensor, including: a substrate; at least two gas sensing units, which are located on the semiconductor substrate, wherein each gas sensing unit comprises a heterojunction, a source electrode and a drain electrode which are located above the heterojunction, and a grid electrode formed by functional film layers, the heterojunction between the gas sensing units is isolated from each other, the functional film layers are used for detecting gas, and the gas which can be detected by the functional film layers in different gas sensing units is different;
a passivation layer covering all device regions except the functional film layer.
In a second aspect, an embodiment of the present invention further provides a method for manufacturing a gas sensor, where the method includes:
providing a substrate;
forming at least two gas sensing units on the substrate, wherein the gas sensing units comprise heterojunctions, source electrodes and drain electrodes which are positioned above the heterojunctions, and grid electrodes which are formed by functional film layers, the heterojunctions among the gas sensing units are mutually isolated, the functional film layers are used for detecting gases, and the gases which can be detected by the functional film layers in different gas sensing units are different;
forming a passivation layer on the gas sensing cell, wherein the passivation layer covers all of the device region except the functional film layer.
The present invention provides a gas sensor, comprising: a substrate; the gas sensing units are positioned on the semiconductor substrate and comprise heterojunctions, source electrodes and drain electrodes positioned on the heterojunctions and grid electrodes formed by functional film layers, wherein the heterojunctions among the gas sensing units are mutually isolated, the functional film layers are used for detecting gas, the gas which can be detected by the functional film layers in different gas sensing units is different, and the passivation layer covers all device areas except the functional film layers. The problem of the design of the existing gas sensor of different usage all be that the design of individual encapsulation can have the maintenance cost that improves detecting system is solved, realize the gas sensor integration of a plurality of different functions, reduce cost's effect.
Drawings
FIG. 1 is a schematic diagram of a gas sensor in an embodiment of the invention;
FIG. 2 is a schematic top view of a gas sensor according to an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of a heterojunction of a gas sensor in an embodiment of the invention;
FIG. 4 is a flow chart of a method of making a gas sensor in an embodiment of the invention;
FIG. 5 is a flow chart of a method of making a gas sensor cell in an embodiment of the invention;
fig. 6 to 15 are a top view and a cross-sectional view of a gas sensor corresponding to each main flow of a method for manufacturing a gas sensor according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Fig. 1 is a schematic structural diagram of a gas sensor provided in an embodiment of the present invention. The gas sensor provided by the embodiment of the invention can be obtained by the preparation method of the gas sensor provided by any embodiment of the invention.
Illustratively, referring to fig. 1, the gas sensor includes a substrate 1;
the gas sensing units are positioned on the substrate 1 and comprise heterojunctions, and source electrodes, drain electrodes and grid electrodes formed by functional film layers, wherein the heterojunctions among the gas sensing units are mutually isolated, the functional film layers are used for detecting gas, and the gas which can be detected by the functional film layers in different gas sensing units is different;
and a passivation layer covering the entire device region except for the functional film layer. Herein, the entire device region excluding the functional film layer means a region extending to no heterojunction.
Exemplarily, referring to fig. 1, the gas sensor includes at least two gas sensing units, fig. 1 exemplarily shows a schematic structural diagram of a gas sensor including three gas sensing units, namely a first gas sensing unit 100, a second gas sensing unit 200, and a third gas sensing unit 300, wherein the first gas sensing unit 100, the second gas sensing unit 200, and the third gas sensing unit 300 are all located on a substrate 1, wherein the substrate 1 may be a sapphire substrate, and each gas sensing unit is grown on the substrate 1. Each gas sensing cell comprises a heterojunction, a source electrode, a drain electrode and a functional film layer grid electrode, wherein the source electrode, the drain electrode and the functional film layer grid electrode are positioned above the heterojunction, namely, the first gas sensing cell 100 comprises a heterojunction 110, a drain electrode 120, a source electrode 130 and a first functional film layer grid electrode 140, the second gas sensing cell 200 comprises a heterojunction 210, a drain electrode 220, a source electrode 230 and a second functional film layer grid electrode 240, and the third gas sensing cell 300 comprises a heterojunction 310, a drain electrode 320, a source electrode 330 and a third functional film layer grid electrode 340. Wherein the heterojunction 110 of the first gas sensing cell 100, the heterojunction 210 of the second gas sensing cell 200 and the heterojunction 310 of the third gas sensing cell 300 are isolated from each other, so that the different gas sensing cells are independent from each other on the same substrate 1. The first functional layer gate 140, the second functional layer gate 240 and the third functional layer gate 340 are respectively used for detecting gases, and because the functional layers are made of different materials, the gases detected by the different functional layers are different. The gas sensor further includes a passivation layer, each of the gas sensing cells having a passivation layer, and the passivation layer 5 is for covering a region of the first gas sensing cell 100 except the first functional film gate electrode 140, a region of the second gas sensing cell 200 except the second functional film gate electrode 240, and a region of the third gas sensing cell 300 except the third functional film gate electrode 340.
Optionally, with continued reference to fig. 1, the heterojunction of each gas sensing unit is located in the same layer and the material of the corresponding film layer is the same.
Specifically, referring to fig. 1, the heterojunction 110 of the first gas sensing cell 100, the heterojunction 210 of the second gas sensing cell 200, and the heterojunction 310 of the third gas sensing cell 300 are located at the same layer, and the film layer materials of the corresponding heterojunctions are the same.
Optionally, referring to fig. 1, an isolation groove 2 for isolating the heterojunction is disposed between any two adjacent gas sensing units.
Specifically, for example, referring to fig. 1, an isolation trench 2 is disposed between the first gas sensing cell 100 and the second gas sensing cell 200, an isolation trench 2 is disposed between the second gas sensing cell 200 and the third gas sensing cell 300, and the isolation trench 2 is used for isolating the heterojunction 110 of the first gas sensing cell 100 from the heterojunction 210 of the second gas sensing cell 200, and isolating the heterojunction 210 of the second gas sensing cell 200 from the heterojunction 310 of the third gas sensing cell 300. The gas sensing units are isolated by the isolation grooves, so that the gas sensing units are mutually independent areas on the substrate, and mutual interference among different gas sensing units is prevented.
Alternatively, referring to fig. 1, the passivation layer covers the inner wall of the isolation trench.
Specifically, for example, referring to fig. 1, a passivation layer 3 covers the inner wall of the isolation trench 2, and is used to further separate the heterojunction 110 of the first gas sensing cell 100 from the heterojunction 210 of the second gas sensing cell 200, separate the heterojunction 210 of the second gas sensing cell 200 from the heterojunction 310 of the third gas sensing cell 300, protect the independence of each gas sensing cell, and prevent interference between two adjacent gas sensing cells from affecting the functional performance of each gas sensing cell.
Fig. 2 is a schematic top view of a gas sensor according to a first embodiment of the present invention. Referring to fig. 2, each gas sensing cell further includes a package pin;
the package pins include a gate pin electrically connected to the gate, a source pin electrically connected to the source, and a drain pin electrically connected to the drain. The source pins in the gas sensing units are electrically connected with each other.
Specifically, for example, referring to fig. 2, the package pins of the first gas sensing cell 100 include a gate pin P1 electrically connected to the gate, a drain pin P2 electrically connected to the drain, and a source pin electrically connected to the source, the package pins of the second gas sensing cell 200 include a gate pin P3 electrically connected to the gate, a drain pin P4 electrically connected to the drain, and a source pin electrically connected to the source, and the package pins of the third gas sensing cell 300 include a gate pin P5 electrically connected to the gate, a drain pin P6 electrically connected to the drain, and a source pin electrically connected to the source, wherein the source pin of the first gas sensing cell 100, the source pin of the second gas sensing cell 200, and the source pin of the third gas sensing cell 300 are connected to each other on the same electrode pin P7, i.e., a common source.
Alternatively, referring to fig. 1 and 2, the material of the functional film layer includes platinum (Pt), lanthanum oxide (La)2O3) And tin dioxide (SnO)2) One kind of (1).
Specifically, for example, referring to fig. 1 and 2, the material of the functional film layer of each gas sensing unit may be platinum (Pt), lanthanum oxide (La)2O3) And tin dioxide (SnO)2) One kind of (1). For example, the material of the first functional film layer 150 of the first gas sensing unit 100 may be platinum (Pt), lanthanum oxide (La)2O3) And tin dioxide (SnO)2) Second work of the second gas sensing cell 200The material of the performance membrane layer 250 may be platinum (Pt) or lanthanum oxide (La)2O3) And tin dioxide (SnO)2) The material of the third functional film layer of the third gas sensing unit 300 may be platinum (Pt), lanthanum oxide (La)2O3) And tin dioxide (SnO)2) One kind of (1).
Fig. 3 is a schematic structural diagram of a heterojunction of a gas sensor provided in an embodiment of the present invention. Referring to fig. 3, the heterojunction includes a GaN channel layer 3 and an AlGaN barrier layer 4 which are laminated, the AlGaN barrier layer 4 being located on a side of the GaN channel layer 3 remote from the substrate 1. Optionally, a buffer layer 6 and an AIN layer 7 may be further included between the substrate 1 and the heterojunction of the gas sensor, the buffer layer is used for reducing stress, reducing defect density and electrically insulating, the buffer layer may be made of GaN, and the AIN layer is located on the buffer layer. Optionally, a GaN layer 8 is further included between the AlGaN barrier layer 4 and the source and drain electrodes (the source and drain electrodes are in the same layer), and the GaN layer 8 is used to improve the ohmic contact characteristics between the AlGaN barrier layer 4 and the source electrode and between the AlGaN barrier layer 4 and the drain electrode.
Specifically, exemplarily, referring to fig. 1 to 3, a buffer layer 6 is located on a substrate 1, an AIN layer 7 is located on the buffer layer 6, and heterojunctions of the respective gas sensing units are located on the same layer and are all located on the AIN layer 7. The heterojunction 110 of the first gas sensing cell 100 includes an AlGaN barrier layer 112 and a GaN channel layer 111, the heterojunction 210 of the second gas sensing cell 200 includes an AlGaN barrier layer 212 and a GaN channel layer 211, and the heterojunction 310 of the third gas sensing cell 300 includes an AlGaN barrier layer 312 and a GaN channel layer 311. Wherein the drain 120 of the first gas sensing cell 100 forms an ohmic contact with the AlGaN barrier layer 112, and the source 130 forms an ohmic contact with the AlGaN barrier layer 112; the drain 220 of the second gas sensing cell 200 forms an ohmic contact with the AlGaN barrier layer 212, and the source 230 forms an ohmic contact with the AlGaN barrier layer 212; the drain 320 of the third gas-sensing cell 300 forms an ohmic contact with the AlGaN barrier 312 and the source 330 forms an ohmic contact with the AlGaN barrier 312.
Wherein, the metal film layer commonly used for the source electrode and the drain electrode is Ti/Al/X/Au (wherein, the common X is Ti, Ni, Mo, etc.)
In the technical solution of this embodiment, the gas sensor can be used for detecting the components of the gas and the concentration of the gas, and the operating principle thereof is as follows: for example, referring to fig. 1 to 3, assuming that the material adopted by the first functional film layer gate 140 of the first gas sensing unit 100 is platinum (Pt), H can be tested2、NH3、NO2And the like; the material used for the second functional film gate electrode 240 of the second gas sensing cell 200 is lanthanum oxide (La)2O3) Can test CO2The material used for the third functional film grid 340 of the third gas sensing unit 300 is tin dioxide (SnO)2) Ozone can be tested. When the component of a certain gas and the concentration of the contained gas need to be detected, the source and the drain are connected to a constant voltage power supply, the gas sensor is contacted with the gas to be detected, if the change of the current signal of the gate pin P1 of the first gas sensing unit 100 is detected, the gas is possibly H2、NH3、NO2Gas, and the concentration of the gas component can be judged by observing the amplitude of the voltage signal, if no electric signal is detected, the gas is not H2、NH3、NO2A gas; the basis for this determination is: the functional film of the first functional film gate 140 of the first gas sensing unit 100 is made of platinum (Pt), when H is2、NH3、NO2When the gas contacts the first functional film layer platinum (Pt), a corresponding chemical reaction occurs in the first functional film layer gate 140 region, the generated chemical reaction affects the concentration of the two-dimensional electron gas generated by the heterojunction 110, so as to convert the chemical signal into an electrical signal, and if the gas concentration is higher and the speed of the chemical reaction is higher, the amplitude of the chemical signal converted into the electrical signal is larger, so that the change of the current signal can be detected through the gate pin P1, and the amplitude of the change of the current signal can be detected. If a change in the current signal at the gate pin P3 of the second gas-sensing cell 200 is detected, the gas is said to be CO2And the concentration of the gas component can be determined by observing the amplitude of the change of the current signal, ifNo change in current signal was detected, indicating that the gas was not CO2The basis for this determination is: the material used for the second functional film gate electrode 240 of the second gas sensor cell 200 is lanthanum oxide (La)2O3) When CO is present2With a second functional film layer of lanthanum oxide (La)2O3) When contacting, a corresponding chemical reaction occurs in the second functional film layer gate 240 region, and the generated chemical reaction affects the concentration of the two-dimensional electron gas generated by the heterojunction 210, so as to convert the chemical signal into an electrical signal, and if the gas concentration is higher and the chemical reaction speed is higher, the change amplitude of the current signal is larger, so that the current signal change can be detected through the gate pin P3, and the change amplitude of the current signal can be detected. If the gate pin P5 of the third gas sensing cell 300 is detected to have a current signal change, the gas is ozone, and the concentration of the gas component can be determined by observing the magnitude of the current signal change, and if no electrical signal change is detected, the gas is not ozone, which is determined according to the following steps: the functional film of the third functional film gate 340 of the third gas sensing unit 300 is tin dioxide (SnO)2) When the ozone and the third functional film layer stannic oxide (SnO)2) When contacting, a corresponding chemical reaction occurs in the third functional film layer gate 340 area, and the generated chemical reaction affects the concentration of the two-dimensional electron gas generated by the heterojunction 310, so as to convert the chemical signal into an electrical signal, and if the gas has a higher composition and the chemical reaction speed is faster, the magnitude of the change of the chemical signal into the current signal is larger, so that the current signal change can be detected through the gate pin P5, and the magnitude of the current signal change can be detected.
It should be noted that, the above embodiments are only exemplary illustrations given for the gas sensor to include three gas sensing units, the number of the gas sensing units includes at least two, the number and the type of the functional membrane material are set according to actual needs, and the number is not limited specifically here.
An embodiment of the present invention provides a gas sensor, including: a substrate; the gas sensing units are positioned on the semiconductor substrate and comprise heterojunctions, source electrodes and drain electrodes positioned on the heterojunctions and grid electrodes formed by functional film layers, wherein the heterojunctions among the gas sensing units are mutually isolated, the functional film layers are used for detecting gas, the gas which can be detected by the functional film layers in different gas sensing units is different, and the passivation layer covers all device areas except the functional film layers. The problem of current gas sensor's of different usage design all be that the design of carrying out alone encapsulation can have the maintenance cost that improves detecting system is solved, realized the gas sensor integration with a plurality of different functions, reduce cost's effect.
Fig. 4 is a flowchart of a method for manufacturing a gas sensor provided in an embodiment of the present invention, where this embodiment is applicable to an implementation process of a gas sensor, and the method is used to manufacture a gas sensor according to any embodiment of the present invention, and specifically includes the following steps:
Wherein the substrate may be a sapphire substrate.
At step 420, at least two gas sensing cells are formed on the substrate.
Each gas sensing unit is located on the same substrate and comprises a heterojunction, a source electrode and a drain electrode which are located on the heterojunction, and a grid electrode formed by a functional film layer. The heterojunction among the gas sensing units is mutually isolated, the functional film layers of the gas sensing units are used for detecting gas, and the gas which can be detected by the functional film layers in different gas sensing units is different.
Wherein the passivation layer covers all of the device region except the functional film layer. The passivation layer is used for protecting a source electrode, a drain electrode and a grid electrode in each gas sensing unit, avoiding interference among the gas sensing units due to mutual contact, and preventing damage generated in use.
Fig. 5 is a flowchart of a method of manufacturing a gas sensor unit provided in an embodiment of the present invention. Alternatively, referring to fig. 5, the step of forming at least two gas sensing cells on the substrate includes:
and 421, sequentially epitaxially growing a GaN channel layer and an AlGaN barrier layer on the substrate to form a heterojunction.
Illustratively, referring to fig. 6 and 7, a heterojunction 5 formed by a GaN channel layer 3 and an AlGaN barrier layer 4 is epitaxially grown on a substrate in this order.
And 422, etching the heterojunction between any two adjacent device areas until the heterojunction at least penetrates through the AlGaN barrier layer to form an isolation groove.
And etching the heterojunction between two adjacent gas sensing units by adopting a plasma etching method until at least the AlGaN barrier layer penetrates through the AlGaN barrier layer to form an isolation groove, wherein the formed isolation groove 2 refers to the graph 8 and the graph 9. In addition, the isolation trench 2 may be formed by ion implantation.
And 423, forming a source electrode and a drain electrode on the heterojunction of each device area by adopting a micro-nano manufacturing process.
Based on the above steps, exemplarily, referring to fig. 10 and 11, a micro-nano manufacturing process is used to sequentially form a source ohmic contact and a drain ohmic contact on the regions corresponding to the source and the drain of each gas sensing cell. The micro-nano manufacturing process comprises the steps of removing surface oxides, metal deposition and patterning treatment and high-temperature annealing treatment in sequence.
And 424, forming a functional film layer grid on the heterojunction of each device region by adopting a micro-nano manufacturing process.
In addition to the above steps, for example, referring to fig. 12 and 13, a micro-nano manufacturing process is used to form a gate electrode in each region corresponding to the gate electrode of each gas sensing unit, where the gate electrode is a functional film layer.
Illustratively, referring to fig. 2, on the basis of the above steps, the source, drain and gate of each gas sensing cell are fabricated with plates as pins. The sources of the gas sensing units share one polar plate, namely a common source.
Illustratively, referring to fig. 14 and 15, on the basis of the above steps, a passivation layer 5 is provided for each gas sensing cell to protect the device and improve the device reliability unless both the plate and the gate of the device region are covered.
It should be noted that, the above embodiments are only exemplary illustrations given for the gas sensor to include three gas sensing units, the number of the gas sensing units includes at least two, the number and the type of the functional membrane material are set according to actual needs, and the number is not limited specifically here.
According to the technical scheme of the embodiment, the substrate is provided by providing the preparation method of the gas sensor; forming at least two gas sensing units on a substrate, wherein the gas sensing units comprise heterojunctions, and a source electrode, a drain electrode and a grid electrode which are formed by functional film layers and are positioned on the heterojunctions, the heterojunctions among the gas sensing units are mutually isolated, the functional film layers are used for detecting gas, and the gas which can be detected by the functional film layers in different gas sensing units is different; and forming a passivation layer on the gas sensing unit, wherein the passivation layer covers all the device region except the functional film layer. The problem of current gas sensor's of different usage design all be that the design of carrying out alone encapsulation can have the maintenance cost that improves detecting system is solved, realized the gas sensor integration with a plurality of different functions, reduce cost's effect.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (10)
1. A gas sensor, comprising:
a substrate;
at least two gas sensing units, which are located on the substrate, wherein each gas sensing unit comprises a heterojunction, a source electrode and a drain electrode which are located above the heterojunction, and a grid electrode formed by functional film layers, the heterojunction among the gas sensing units is isolated from each other, the functional film layers are used for detecting gas, and the gas which can be detected by the functional film layers in different gas sensing units is different;
a passivation layer covering all device regions except the functional film layer.
2. The gas sensor according to claim 1, wherein the heterojunction of each gas sensing cell is located in the same layer and the materials of the corresponding film layers are the same.
3. The gas sensor according to claim 2, wherein an isolation groove for isolating the heterojunction is provided between any two adjacent gas sensing cells.
4. The gas sensor according to claim 3, wherein the passivation layer covers an inner wall of the isolation trench.
5. The gas sensor of claim 1, wherein each of the gas sensing cells further comprises a package pin;
the package pins include a gate pin electrically connected to the gate, a source pin electrically connected to the source, and a drain pin electrically connected to the drain.
6. The gas sensor according to claim 5, wherein the source pins in each of the gas sensing cells are electrically connected to each other.
7. The gas sensor according to any of claims 1-6, wherein the material of the functional membrane layer comprises platinum Pt, lanthanum oxide La2O3And tin dioxide SnO2One kind of (1).
8. The gas sensor according to any one of claims 1 to 6, wherein the heterojunction comprises a GaN channel layer and an AlGaN barrier layer stacked, the AlGaN barrier layer being located on a side of the GaN channel layer remote from the semiconductor substrate.
9. A method of making a gas sensor, comprising:
providing a substrate;
forming at least two gas sensing units on the substrate, wherein the gas sensing units comprise heterojunctions, source electrodes and drain electrodes which are positioned above the heterojunctions, and grid electrodes which are formed by functional film layers, the heterojunctions among the gas sensing units are mutually isolated, the functional film layers are used for detecting gases, and the gases which can be detected by the functional film layers in different gas sensing units are different;
forming a passivation layer on the gas sensing cell, wherein the passivation layer covers all of the device region except the functional film layer.
10. The method of manufacturing a gas sensor according to claim 9, wherein forming at least two gas sensing cells on the substrate includes:
sequentially epitaxially growing a GaN channel layer and an AlGaN barrier layer on the substrate to form a heterojunction;
etching the heterojunction between any two adjacent device areas until at least the AlGaN barrier layer penetrates through the AlGaN barrier layer to form an isolation groove;
and forming a grid consisting of a source electrode, a drain electrode and a functional film layer on the heterojunction of each device region by adopting a micro-nano manufacturing process.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
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| CN112924515A (en) * | 2021-01-20 | 2021-06-08 | 南方科技大学 | Gas sensor and preparation method thereof |
| CN117705897A (en) * | 2024-02-05 | 2024-03-15 | 合肥美镓传感科技有限公司 | Gallium nitride gas sensor, preparation method thereof and gas detection method |
| CN117705897B (en) * | 2024-02-05 | 2024-05-28 | 合肥美镓传感科技有限公司 | Gallium nitride gas sensor, preparation method thereof and gas detection method |
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