CN115774043A - FET heated finger-inserted gas-sensitive sensor and processing method thereof - Google Patents
FET heated finger-inserted gas-sensitive sensor and processing method thereof Download PDFInfo
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- CN115774043A CN115774043A CN202211372269.3A CN202211372269A CN115774043A CN 115774043 A CN115774043 A CN 115774043A CN 202211372269 A CN202211372269 A CN 202211372269A CN 115774043 A CN115774043 A CN 115774043A
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Abstract
The invention relates to the technical field of sensors, and discloses an FET (field effect transistor) heated finger-inserting gas sensor and a processing method thereof. Wherein the FET heated interdigitated gas sensor comprises: the silicon island structure comprises a substrate, a heat insulation cavity and a silicon island, wherein the heat insulation cavity is arranged on the substrate; the insulating layer is arranged on the same side of the silicon island and the substrate; the FET heating component comprises a source electrode, a grid electrode and a drain electrode, wherein the source electrode and the drain electrode are formed in the silicon island at intervals, the grid electrode is positioned between the source electrode and the drain electrode, and the source electrode and the drain electrode can generate heat when being conducted; an insertion finger sensitive electrode formed on the insulating layer; and the gas-sensitive layer covers the finger-inserting sensitive electrode, and the resistivity change of the gas-sensitive layer can be output through the finger-inserting sensitive electrode. The FET heated finger-inserted gas-sensitive sensor disclosed by the invention has the characteristics of simple structure, easiness in processing, uniform heating, low power consumption and long service life, and is beneficial to the miniaturization and integration design of the FET heated finger-inserted gas-sensitive sensor.
Description
Technical Field
The invention relates to the technical field of sensors, in particular to an FET heated finger-inserted gas sensor and a processing method thereof.
Background
The existing gas sensor needs to separately design a heating coil and a sensitive electrode, the gas sensor with the structure has the problems of uneven heating, metal atom migration and film crack, the stability of the gas sensor is reduced, in addition, the processing technology of multilayer metal needs to be considered, the processing difficulty of the gas sensor is increased, and the mass production of the gas sensor is not facilitated.
Disclosure of Invention
Based on the above, the invention aims to provide an FET heated interdigital gas sensor and a processing method thereof, which solve the problems of uneven heating, metal atom migration and film crack generation in the prior art, reduce the processing difficulty of the FET heated interdigital gas sensor and are beneficial to the batch production of the FET heated interdigital gas sensor.
In order to achieve the purpose, the invention adopts the following technical scheme:
a FET heated interdigitated gas sensor comprising: the silicon island structure comprises a substrate, a heat insulation cavity and a silicon island, wherein the heat insulation cavity is arranged on the substrate, the silicon island is arranged in the heat insulation cavity, and the silicon island and the substrate are arranged at intervals; the insulating layer is arranged on the same side of the silicon island and the substrate; the FET heating component comprises a source electrode, a grid electrode and a drain electrode, wherein the source electrode and the drain electrode are formed in the silicon island at intervals, the grid electrode is positioned in the insulating layer and positioned between the source electrode and the drain electrode, and the source electrode and the drain electrode can generate heat when being conducted; an insertion finger sensitive electrode formed on the insulating layer; and the gas-sensitive layer covers the finger-inserting sensitive electrode, and the resistivity change of the gas-sensitive layer can be output through the finger-inserting sensitive electrode.
As a preferable scheme of the FET heated finger-inserted gas sensor, the finger-inserted gas sensor is a platinum electrode, a gold electrode or a titanium nitride electrode.
As a preferable scheme of the FET-heated interdigitated gas sensor, the side wall of the heat insulation chamber extends along the axial direction of the substrate, or the side wall of the heat insulation chamber and the axial direction of the substrate form an included angle.
As a preferable mode of the FET-heated finger-inserted gas sensor, the insulating layer includes an insulating layer body and a connection layer, the connection layer extends outward along one end of the insulating layer body, and an extension line of the connection layer passes through a center of the insulating layer body.
As a preferable mode of the FET-heated interdigitated gas sensor, the gate electrode is formed between the silicon island and the insulating layer and is a polysilicon electrode.
A processing method of the FET heated interdigitated gas sensor suitable for any one of the above technical solutions comprises the following steps:
providing a substrate, and infiltrating ions into a local area of the substrate to form a silicon island;
forming an insulating layer, a source electrode, a drain electrode and a grid electrode on the silicon island, wherein the source electrode and the drain electrode are arranged in the silicon island at intervals, and the grid electrode is positioned in the insulating layer and between the source electrode and the drain electrode;
processing a heat insulation chamber on the substrate, wherein the silicon island and the substrate are arranged at intervals;
forming an insertion sensitive electrode on the insulating layer;
forming a gas-sensitive layer for detecting the content of sensitive gas on the finger-inserted sensitive electrode to form a semi-finished product;
and annealing and cooling the semi-finished product to form the FET heated finger-inserting gas-sensitive sensor.
As a preferable embodiment of the processing method of the FET-heated interdigitated gas sensor, the gate is a polysilicon electrode, and the forming of the polysilicon electrode includes:
forming a first sub-insulating layer on the silicon island and the substrate;
forming a polysilicon layer on the first sub-insulating layer;
forming a first stop layer on the polycrystalline silicon layer;
patterning the first stop layer to form an etching opening;
etching the polysilicon layer facing the etching opening;
and removing the patterned first stop layer, and forming the polysilicon electrode by using the residual polysilicon layer.
As a preferable mode of the processing method of the FET-heated interdigital gas sensor, when the interdigital sensitive electrode is formed in the insulating layer, the method includes:
forming a second sub-insulating layer on the substrate, the silicon island, the first sub-insulating layer and the gate, wherein the first sub-insulating layer and the second sub-insulating layer form an insulating layer;
forming a second stopper layer on the insulating layer;
patterning the second stop layer to form a filling opening;
etching the insulating layer facing the filling opening to form an electrode groove;
sputtering or chemical vapor deposition of a conductive material into the electrode groove;
and removing the patterned second stop layer, and filling the conductive material in the electrode groove to form the insertion sensitive electrode.
As a preferred scheme of a processing method of the FET heated finger-inserted gas sensor, a screen printing method is adopted to drip and coat a gas sensitive material on the finger-inserted sensitive electrode, or an evaporation method is adopted to form the gas sensitive material on the finger-inserted sensitive electrode to form the gas sensitive layer.
As a preferable scheme of a processing method of the FET-heated interdigitated gas sensor, the substrate is P-type silicon, the silicon island is an N-well silicon island doped with phosphorus ions on the P-type silicon, and the source and the drain are formed by doping boron ions on the N-well silicon island.
The invention has the beneficial effects that:
the FET-heated finger-inserted gas-sensitive sensor disclosed by the invention integrates the FET heating component and the finger-inserted sensitive electrode, has a simple structure, is beneficial to batch production of the gas-sensitive sensor, heats the gas-sensitive layer by using the Joule heat of a field effect transistor of the FET heating component, is more uniform in heating, can reduce the power consumption of a system, does not have the problem of metal atom migration in the heating process because of not containing metal atoms, increases the stability of the FET-heated finger-inserted gas-sensitive sensor, reduces the probability of film cracks of the FET-heated finger-inserted gas-sensitive sensor, and promotes the miniaturization and integration of the FET-heated finger-inserted gas-sensitive sensor.
The processing method of the FET-heated finger-inserting gas-sensitive sensor disclosed by the invention is simple in process and beneficial to batch production of the gas-sensitive sensor, and the processed FET-heated finger-inserting gas-sensitive sensor has the characteristics of uniform heating, low power consumption and long service life and is beneficial to miniaturization and integration design of the FET-heated finger-inserting gas-sensitive sensor.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the contents of the embodiments of the present invention and the drawings without creative efforts.
FIG. 1 is a cross-sectional view of a FET heated interdigitated gas sensor provided in accordance with an embodiment of the present invention;
FIG. 2 is a top view of a FET heater assembly of a FET heated interdigitated gas sensor provided in accordance with an embodiment of the present invention;
FIG. 3 is a top view of an interdigitated sensitive electrode of a FET heated interdigitated gas sensor provided in accordance with an embodiment of the present invention;
FIG. 4 is a top view of an insulating layer of a FET heated interdigitated gas sensor provided in accordance with an embodiment of the present invention;
FIG. 5 is a cross-sectional view of a FET heated interdigitated gas sensor according to a first alternative embodiment of the present invention;
FIG. 6 is a cross-sectional view of a FET heated interdigitated gas sensor of a second alternative embodiment of the present invention;
FIG. 7 is a flow chart of a method of manufacturing a FET heated interdigitated gas sensor according to an embodiment of the present invention;
fig. 8 to 24 are process diagrams of a processing method of the FET-heated interdigitated gas sensor according to the embodiment of the present invention.
In the figure:
1. a substrate; 10. a thermally insulated chamber; 11. a silicon island;
2. an insulating layer; 20. an electrode tank; 201. a first sub-insulating layer; 202. a second sub-insulating layer; 21. an insulating layer body; 22. a connecting layer;
3. a FET heating component; 31. a source electrode; 32. a drain electrode; 33. a gate electrode; 330. a polysilicon layer;
4. an insertion finger sensitive electrode;
5. a gas-sensitive layer;
61. a first stopper layer; 610. etching an opening; 62. a second stopper layer; 620. filling the opening;
71. a first photoresist layer; 710. a first opening region; 72. a second photoresist layer; 720. a second opening region; 73. a protective layer; 74. a hard mask; 740. a heat insulation hole; 75. a third photoresist layer; 750. a third opened region.
Detailed Description
In order to make the technical problems solved, technical solutions adopted and technical effects achieved by the present invention clearer, the technical solutions of the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Wherein the terms "first position" and "second position" are two different positions.
In the description of the present invention, it should be noted that unless otherwise explicitly stated or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection or a removable connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The present embodiment provides an insert finger gas sensor heated by a FET, as shown in fig. 1 and fig. 2, the insert finger gas sensor includes a substrate 1, an insulating layer 2, a FET heating element 3, an insert finger sensitive electrode 4, and a gas sensitive layer 5, a heat insulation chamber 10 is disposed on the substrate 1, a silicon island 11 is disposed in the heat insulation chamber 10, the silicon island 11 and the substrate 1 are disposed at an interval, the insulating layer 2 is disposed on the same side of the silicon island 11 and the substrate 1, the FET heating element 3 includes a source 31, a gate 33, and a drain 32, the source 31 and the drain 32 are formed in the silicon island 11 at an interval, the gate 33 is located in the insulating layer 2, the gate 33 is located between the source 31 and the drain 32, when the source 31 and the drain 32 are turned on, the insert finger sensitive electrode 4 is formed on the insulating layer 2, the gas sensitive layer 5 covers the insert finger sensitive electrode 4, and a change in resistivity of the gas sensitive layer 5 can be output through the insert finger sensitive electrode 4.
The inserting finger gas sensor heated by the FET provided by the embodiment integrates the FET heating component 3 and the inserting finger sensitive electrode 4, the structure is simple, the mass production of the gas sensor is facilitated, the gas sensitive layer 5 is heated by utilizing the Joule heat of the field effect transistor of the FET heating component 3, the heating is more uniform, the system power consumption can be reduced, metal atoms are not contained, the problem of metal atom migration in the heating process is solved, the stability of the inserting finger gas sensor heated by the FET is improved, the probability of film cracks of the inserting finger gas sensor heated by the FET is reduced, and the miniaturization and integration of the inserting finger gas sensor heated by the FET are promoted.
As shown in fig. 2, the source 31 and the drain 32 of the present embodiment are both in the shape of a circular regular octagon, the number of the source 31 and the drain 32 is one, and the source 31 and the drain 32 are distributed at intervals on the silicon island 11. In other embodiments, the source electrode 31 and the drain electrode 32 may also be circular or other annular polygons, the number of the source electrode 31 and the drain electrode 32 may be two or more than two, or the number of the source electrode 31 is one more than that of the drain electrode 32, which is specifically set according to actual needs.
As shown in fig. 3, the finger sensitive electrode 4 of this embodiment is a platinum electrode, a gold electrode or a titanium nitride electrode. The finger-inserted sensitive electrode 4 is used as a sensing electrode of the gas sensitive layer 5, and can sense the change of the resistivity of the gas sensitive layer 5, so as to detect the gas concentration of the sensitive gas. The electrode width and the electrode gap of the finger-inserted sensitive electrode 4 are not limited in this embodiment. In other embodiments, the finger-inserted sensitive electrode 4 can be made of other materials, which are selected according to actual needs. The cross-sectional area of each tooth-shaped electrode of the finger-inserted sensitive electrode 4 of the present embodiment is far smaller than that of the source electrode 31, and the unit area of the finger-inserted sensitive electrode 4 with such a structure is larger, so that the gas sensitive layer 5 can be more effectively sensitive. In other embodiments, the cross-sectional area of each dentate electrode of the interdigitated sensing electrode 4 can also be designed to be similar to or the same as that of the source electrode 31, and is set according to actual needs.
As shown in fig. 1, the sidewall of the insulating chamber 10 of the present embodiment extends along the axial direction of the substrate 1, and the insulating chamber 10 is formed by a dry deep silicon etching process. In other embodiments of the present invention, the sidewall of the thermal insulation chamber 10 may also be disposed at an angle with the axial direction of the substrate 1, as shown in fig. 5, and the thermal insulation chamber 10 is formed by a wet etching process.
As shown in fig. 4, the insulating layer 2 of the present embodiment includes an insulating layer body 21 and a connection layer 22, the connection layer 22 extends outward along one end of the insulating layer body 21, and an extension line of the connection layer 22 passes through the center of the insulating layer body 21. The insulating layer body 21 of this embodiment is the square, the number of articulamentum 22 is four, every articulamentum 22 all is located insulating layer body 21's corner, the angle of the long limit of every articulamentum 22 and insulating layer body 21 and broadside is 135, this kind of structure is compared with the orientation extension of articulamentum 22 along an limit of insulating layer body 21, the effective area of insulating layer 2 has been increased, the robust performance of what FET heated inserts and indicates gas sensor has been promoted, the life of what FET heated inserts and indicates gas sensor has been prolonged, source 31 and drain electrode 32 parcel are between insulating layer 2 and silicon island 11, and silicon island 11 does not contact with substrate 1, the phenomenon of electric leakage takes place when having avoided source 31 and drain electrode 32 to switch on. In other embodiments, the shape of the insulating layer body 21 may also be other shapes that are the same as the shape of the silicon island 11, and is specifically set according to actual needs.
The gate 33 of the present embodiment is formed between the silicon island 11 and the insulating layer 2 and is a polysilicon electrode. In the process of using the heating coil prepared by adopting the platinum material in the prior art, the platinum atoms can migrate at high temperature, the heating coil is not beneficial to heating, cracks can also appear on the heating coil, the normal use of the gas sensor is influenced, and the grid 33 prepared by adopting the polysilicon material cannot have the problems.
The FET heating element 3 of the FET-heated interdigitated gas sensor of the present embodiment can heat the gas sensitive layer 5 to different temperatures under different heating voltages, and experiments show that the FET heating element 3 can heat the gas sensitive layer 5 to temperatures even higher than 350 ℃, and the temperature of the gas sensitive layer 5 is substantially linearly related to the heating voltage.
It should be noted that, in other embodiments of the present invention, the heat insulation chamber 10 may be formed on the side of the substrate 1 where the insulation layer 2 is disposed, and the heat insulation chamber 10 is formed by wet etching, as shown in fig. 6.
This embodiment further provides a method for processing the insert finger gas sensor suitable for heating the FET, as shown in fig. 7, including:
s1, providing a substrate 1, and infiltrating ions into a local area of the substrate 1 to form a silicon island 11.
Specifically, the substrate 1 of the present embodiment is P-type silicon, and S1 includes the following steps:
s11, coating photoresist on the upper surface of the substrate 1 to form a first photoresist layer 71;
s12, patterning the first photoresist layer 71, and forming a first opening region 710 on the first photoresist layer 71;
s13, infiltrating phosphorous ions into the substrate 1 through the first opening region 710, where the substrate 1 doped with the phosphorous ions is an N-well silicon island, as shown in fig. 8;
and S14, removing the patterned first photoresist layer 71, as shown in FIG. 9.
Specifically, the N-well silicon island of the present embodiment has a square shape. In other embodiments, the shape of the N-well silicon island may also be rectangular, circular or other polygonal shapes, which are selected according to actual needs.
And S2, forming a source 31 and a drain 32 on the silicon island 11, wherein the source 31 and the drain 32 are arranged in the silicon island 11 at intervals.
Specifically, when forming the source electrode 31 and the drain electrode 32, S2 includes the steps of:
s21, coating photoresist on the upper surfaces of the substrate 1 and the silicon island 11 to form a second photoresist layer 72;
s22, patterning the second photoresist layer 72, and forming a second open region 720 on the second photoresist layer 72, as shown in fig. 10;
s23, infiltrating boron ions into the silicon island 11 through the second opening region 720, wherein the part of the silicon island 11 doped with boron ions is the source 31 and the drain 32, as shown in fig. 11;
and S24, removing the patterned second photoresist layer 72, as shown in FIG. 12.
Specifically, the shapes of the processed source electrode 31 and drain electrode 32 are both circular regular octagons, the number of the source electrode 31 and drain electrode 32 is one, and the source electrode 31 and drain electrode 32 are distributed on the silicon island 11 at intervals. In other embodiments, the source electrode 31 and the drain electrode 32 may also be circular or other annular polygons, the number of the source electrode 31 and the drain electrode 32 may be two or more than two, or the number of the source electrode 31 is one more than that of the drain electrode 32, which is specifically set according to actual needs.
And S3, forming an insulating layer 2 and a gate 33 on the silicon island 11, wherein the gate 33 is positioned in the insulating layer 2 and between the source 31 and the drain 32.
The gate 33 of this embodiment is a polysilicon electrode, and S3 includes the following steps:
s31, forming a first sub-insulating layer 201 on the silicon island 11, the substrate 1, the source 31 and the drain 32, and forming a polysilicon layer 330 on the first sub-insulating layer 201, as shown in fig. 13;
s32, forming a first stop layer 61 on the polycrystalline silicon layer 330;
s33, patterning the first stop layer 61 to form an etching opening 610, as shown in fig. 14;
s34, etching the polysilicon layer 330 facing the etching opening 610, as shown in FIG. 15;
s35, removing the patterned first stopper layer 61, and forming a polysilicon electrode on the remaining polysilicon layer 330, as shown in fig. 16;
s36, forming a second sub-insulating layer 202 on the substrate 1, the silicon island 11, the first sub-insulating layer 201, and the gate 33, wherein the first sub-insulating layer 201 and the second sub-insulating layer 202 constitute an insulating layer 2, as shown in fig. 17.
The first stopper layer 61 of the present embodiment is a photoresist layer, and the polysilicon electrode is in the shape of a circular regular octagon and is located between the source 31 and the drain 32. In other embodiments, the shape of the polysilicon electrode may also be a linear shape, a circular shape, or another annular polygon, which is set according to actual needs.
Specifically, the insulating layer 2 is formed by a chemical vapor deposition process, and the insulating layer 2 of the present embodiment is a silicon oxide layer. In other embodiments, the insulating layer 2 may also be a single-layer structure formed by an insulating material such as silicon nitride or aluminum oxide, or at least two-layer structure formed by an insulating material such as silicon oxide, silicon nitride, or aluminum oxide, which is specifically selected according to actual needs.
And S4, forming the finger inserting sensitive electrode 4 on the insulating layer 2.
When the finger-inserted sensitive electrode 4 is formed on the insulating layer 2, S4 includes the steps of:
s41, forming a second stopper layer 62 on the insulating layer 2;
s42, patterning the second stop layer 62 to form a filling opening 620;
s43, etching the insulating layer 2 opposite to the filling opening 620 to form an electrode groove 20, as shown in FIG. 18;
s44, conducting materials are sputtered or chemically vapor deposited into the electrode groove 20;
and S45, removing the patterned second stop layer 62, and filling the conductive material in the electrode groove 20 to form the finger-inserted sensitive electrode 4, as shown in FIG. 19.
The second stopper layer 62 of this embodiment is a photoresist layer, and the structure of the finger-inserted sensitive electrode 4 in step S45 is as shown in fig. 3, and the finger-inserted sensitive electrode 4 with this structure can be sensitive to the change of the resistivity of the gas sensitive layer 5, so as to detect the concentration of the sensitive gas. The finger-inserted sensitive electrode 4 is a platinum electrode, a gold electrode, or a titanium nitride electrode, or is made of other conductive materials, and this embodiment is not particularly limited.
And S5, forming a gas-sensitive layer 5 for detecting the content of the sensitive gas on the finger-inserted sensitive electrode 4, as shown in FIG. 20.
And (3) dripping the gas-sensitive material on the finger-inserting sensitive electrode 4 by adopting a screen printing method, or forming the gas-sensitive material on the finger-inserting sensitive electrode 4 by adopting an evaporation method to form a gas-sensitive layer 5, wherein the gas-sensitive layer 5 is in a water droplet shape.
Specifically, the gas-sensitive material of the gas-sensitive layer 5 of this embodiment is tin dioxide, tungsten trioxide or zinc oxide, the noble metal contained in the gas-sensitive layer 5 may be platinum, gold, palladium, rhodium or iridium with a catalytic effect, and the noble metal can reduce the semiconductor barrier of tin dioxide, tungsten trioxide or zinc oxide, and promote the selectivity of the interdigitated gas-sensitive sensor for FET heating.
Of course, in other embodiments of the present invention, the gas-sensitive material may be formed on the finger-inserted sensitive electrode 4 by an evaporation method or an inkjet printing method to form the gas-sensitive layer 5, where S5 includes the following steps:
s51, coating a fourth photoresist layer on the insulating layer 2 and the finger inserting sensitive electrode 4;
s52, patterning the fourth photoresist layer to form a fourth opening region;
s53, forming a gas-sensitive material on the finger inserting sensitive electrode 4 by adopting an evaporation method in the fourth opening area to form a gas-sensitive layer 5;
and S54, removing the patterned fourth photoresist layer.
After S5 and before S6, a protective layer 73 for protecting the gas sensitive layer 5 needs to be formed on the gas sensitive layer 5 and the insulating layer 2, as shown in fig. 21, to avoid damage to the gas sensitive layer 5 when the heat insulating chamber 10 is processed.
And S6, processing a heat insulation chamber 10 at one end of the substrate 1, which is far away from the insulating layer 2, so as to form a semi-finished product.
Specifically, when processing the heat insulation chamber 10, S6 includes the steps of:
s61, chemically depositing an insulating material on the substrate 1 to form a hard mask 74;
s62, coating a third photoresist layer 75 on the hard mask 74;
s63, patterning the third photoresist layer 75 to form a third open region 750;
s64, etching the hard mask 74 facing the third opening area 750 to form a heat insulation hole 740, as shown in FIG. 22;
s65, deep silicon etching is performed on the substrate 1 facing the heat insulation hole 740 to form a heat insulation chamber 10, as shown in FIG. 23;
s66, the patterned third photoresist layer 75 and the hard mask 74 are removed, and the protective layer 73 is removed, as shown in fig. 24.
The dry etching process in step S65 has the advantages of good anisotropy and selectivity, and is low in cost but low in etching rate compared with wet etching. Certainly, in other embodiments of the present invention, the heat insulation chamber 10 may also be formed by using a wet self-stop etching process, for example, wet etching is performed on the substrate 1 by using an etching solution such as a potassium hydroxide solution or a tetramethylammonium hydroxide solution, because the concentration of phosphorus ions in the silicon island 11 is higher than the concentration of boron ions carried in the substrate 1, and the etching rate of the etching solution to the substrate 1 with a low ion concentration is much higher than the etching rate of the silicon island 11, the self-stop effect is shown, the etching rate is fast, the equipment is simple, and the mechanical sensitivity is high, and the processing process is selected according to actual needs during actual processing.
And S7, annealing and cooling the semi-finished product to form the FET heated interdigitated gas sensor.
The semi-finished product in the step is a semi-finished product of the insert finger gas sensor heated by a single FET, and the gas sensitive layer 5 of the insert finger gas sensor heated by the annealed FET is in a hole shape, so that the semi-finished product has higher linearity and sensitivity compared with a process of not annealing and cooling. The annealing temperature and the annealing time length belong to technical means commonly used in the art, and can be set by a person skilled in the art according to actual needs, and the embodiment is not particularly limited.
The processing method of the FET-heated finger-inserting gas-sensitive sensor provided by the embodiment has the advantages that the process is simple, the batch production of the gas-sensitive sensor is facilitated, the processed FET-heated finger-inserting gas-sensitive sensor has the characteristics of uniform heating, low power consumption and long service life, and the miniaturization and integration design of the FET-heated finger-inserting gas-sensitive sensor is facilitated.
In order to process the insulating layer 2 into the shape shown in fig. 4, the insulating layer 2 needs to be etched, specifically, after the insulating layer 2 is formed and before the gas sensing layer 5 is formed, a fifth photoresist layer is formed on the insulating layer 2, the fifth photoresist layer is patterned to form a fifth opening region, the insulating layer 2 opposite to the fifth opening region is etched, so that the insulating layer 2 is formed into the shape shown in fig. 4, and finally, the fifth photoresist layer is removed. In other embodiments, the processing step of the insulating layer 2 may also be, after the formation of the thermal isolation chamber 10 and before the removal of the protection layer 73, forming a sixth photoresist layer on the substrate 1, the insulating layer 2 and the silicon island 11, patterning the sixth photoresist layer to form a sixth open area, etching the insulating layer 2 facing the sixth open area to form the insulating layer 2 into the shape as shown in fig. 4, and finally removing the sixth photoresist layer.
In the manufacture of the FET-heated interdigitated gas sensor shown in fig. 6, the heat-insulating chamber 10 is formed by wet etching after the insulating layer 2 is formed, and this step is performed before the gas-sensitive layer 5 is formed in order to reduce the influence on the gas-sensitive layer 5, which is not limited in this embodiment.
In other embodiments of the present invention, the gate 33 may be processed first, and then the source electrode 31 and the drain electrode 32 are processed, which is selected according to actual needs.
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 FET heated interdigitated gas sensor comprising:
the silicon island structure comprises a substrate, a heat insulation cavity and a silicon island, wherein the heat insulation cavity is arranged on the substrate, the silicon island is arranged in the heat insulation cavity, and the silicon island and the substrate are arranged at intervals;
the insulating layer is arranged on the same side of the silicon island and the substrate;
the FET heating component comprises a source electrode, a grid electrode and a drain electrode, wherein the source electrode and the drain electrode are formed in the silicon island at intervals, the grid electrode is positioned in the insulating layer and is positioned between the source electrode and the drain electrode, and the source electrode and the drain electrode can generate heat when being conducted;
the finger-inserting sensitive electrode is formed on the insulating layer;
and the gas-sensitive layer covers the finger-inserting sensitive electrode, and the resistivity change of the gas-sensitive layer can be output through the finger-inserting sensitive electrode.
2. The FET heated interdigitated gas sensor of claim 1, wherein the interdigitated sensing electrode is a platinum electrode, a gold electrode, or a titanium nitride electrode.
3. The FET heated interdigitated gas sensor of claim 1, wherein the sidewall of the insulating chamber extends along the axial direction of the substrate, or the sidewall of the insulating chamber is disposed at an angle to the axial direction of the substrate.
4. A FET heated interdigitated gas sensor as claimed in claim 1 wherein the insulating layer comprises an insulating layer body and a tie layer, the tie layer extending outwardly along one end of the insulating layer body, the extension of the tie layer passing through the centre of the insulating layer body.
5. The FET heated interdigitated gas sensor of claim 1, wherein the gate is formed between the silicon island and the insulating layer and is a polysilicon electrode.
6. A method of manufacturing a FET-heated gas sensor adapted for use in accordance with any of claims 1 to 5, comprising:
providing a substrate, and infiltrating ions into a local area of the substrate to form a silicon island;
forming an insulating layer, a source electrode, a drain electrode and a grid electrode on the silicon island, wherein the source electrode and the drain electrode are arranged in the silicon island at intervals, and the grid electrode is positioned in the insulating layer and between the source electrode and the drain electrode;
processing a heat insulation chamber on the substrate, wherein the silicon island and the substrate are arranged at intervals;
forming an insertion sensitive electrode on the insulating layer;
forming a gas-sensitive layer for detecting the content of sensitive gas on the finger-inserted sensitive electrode to form a semi-finished product;
and annealing and cooling the semi-finished product to form the FET heated finger-inserting gas-sensitive sensor.
7. The method of claim 6, wherein the grid electrode is a polysilicon electrode, and forming the polysilicon electrode comprises:
forming a first sub-insulating layer on the silicon island and the substrate;
forming a polysilicon layer on the first sub-insulating layer;
forming a first stop layer on the polycrystalline silicon layer;
patterning the first stop layer to form an etching opening;
etching the polysilicon layer facing the etching opening;
and removing the patterned first stop layer, and forming the polysilicon electrode by using the residual polysilicon layer.
8. The method of claim 7, wherein forming the finger-sensitive electrode in the insulating layer comprises:
forming a second sub-insulating layer on the substrate, the silicon island, the first sub-insulating layer and the gate, wherein the first sub-insulating layer and the second sub-insulating layer form an insulating layer;
forming a second stopper layer on the insulating layer;
patterning the second stop layer to form a filling opening;
etching the insulating layer opposite to the filling opening to form an electrode groove;
sputtering or chemical vapor deposition of a conductive material into the electrode groove;
and removing the patterned second stop layer, and filling the conductive material in the electrode groove to form the finger insertion sensitive electrode.
9. The method as claimed in claim 6, wherein the gas-sensitive layer is formed by applying a gas-sensitive material onto the finger-inserted sensitive electrode by screen printing or by forming a gas-sensitive material on the finger-inserted sensitive electrode by evaporation.
10. The method of claim 6, wherein the substrate is P-type silicon, the silicon island is an N-well silicon island doped with phosphorus ions on the P-type silicon, and the source and the drain are formed by doping boron ions on the N-well silicon island.
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| CN117783220A (en) * | 2023-12-21 | 2024-03-29 | 南京邮电大学 | A gas sensor and its processing method |
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