A FET-heated interdigital gas sensor and its processing method

Abstract

The present invention relates to the field of sensor technology, and discloses a FET-heated interdigital gas sensor and a processing method thereof. The FET-heated interdigital gas sensor comprises: a substrate, on which an insulating chamber is provided, a silicon island is provided in the insulating chamber, and the silicon island is spaced apart from the substrate; an insulating layer is provided on the same side of the silicon island and the substrate; a FET heating component, including a source, a gate and a drain, the source and the drain are spaced apart and formed in the silicon island, the gate is located between the source and the drain, and the source and the drain can generate heat when they are turned on; an interdigital sensitive electrode is formed on the insulating layer; a gas-sensitive layer is covered on the interdigital sensitive electrode, and the resistivity change of the gas-sensitive layer can be output through the interdigital sensitive electrode. The FET-heated interdigital gas sensor disclosed by the present invention has a simple structure, is easy to process, has the characteristics of uniform heating, low power consumption and long life, and is conducive to the miniaturization and integrated design of the FET-heated interdigital gas sensor.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a FET-heated interdigital gas sensor and a processing method thereof. Background Art

[0002] Existing gas sensors require separately designed heating coils and sensitive electrodes. Gas sensors with this structure have problems such as uneven heating, metal atom migration, and membrane cracks, which reduce the stability of the gas sensor. In addition, the processing technology of multi-layer metals needs to be considered, which increases the processing difficulty of the gas sensor and is not conducive to the mass production of gas sensors. Summary of the Invention

[0003] Based on the above, the purpose of the present invention is to provide a FET-heated interdigital gas sensor and a processing method thereof, which solves the problems of uneven heating, metal atom migration and membrane cracks in the prior art, reduces the processing difficulty of the FET-heated interdigital gas sensor, and facilitates the mass production of the FET-heated interdigital gas sensor.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A FET-heated interdigital gas sensor comprises: a substrate, on which is provided a thermal insulation chamber, wherein a silicon island is provided in the thermal insulation chamber, and the silicon island is spaced apart from the substrate; an insulating layer, arranged on the same side of the silicon island and the substrate; a FET heating component, comprising a source, a gate, and a drain, wherein the source and the drain are spaced apart and formed in the silicon island, the gate is located in the insulating layer and between the source and the drain, and the source and the drain can generate heat when turned on; an interdigital sensitive electrode, formed on the insulating layer; and a gas-sensitive layer, covering the interdigital sensitive electrode, wherein a resistivity change of the gas-sensitive layer can be output through the interdigital sensitive electrode.

[0006] As a preferred solution of a FET-heated interdigital gas sensor, the interdigital sensitive electrode is a platinum electrode, a gold electrode or a titanium nitride electrode.

[0007] As a preferred solution of a FET-heated interdigital gas sensor, the sidewall of the thermal insulation chamber extends along the axial direction of the substrate, or the sidewall of the thermal insulation chamber is arranged at an angle to the axial direction of the substrate.

[0008] As a preferred solution of a FET-heated interdigital gas sensor, the insulating layer includes an insulating layer body and a connecting layer. The connecting layer extends outward along one end of the insulating layer body, and the extension line of the connecting layer passes through the center of the insulating layer body.

[0009] As a preferred solution of the FET-heated interdigital gas sensor, the gate is formed between the silicon island and the insulating layer and is a polysilicon electrode.

[0010] A method for processing a FET-heated interdigital gas sensor applicable to any of the above technical solutions comprises:

[0011] providing a substrate, and implanting ions into a local region of the substrate to form a silicon island;

[0012] forming an insulating layer, a source electrode, a drain electrode, and a gate electrode on the silicon island, wherein the source electrode and the drain electrode are spaced apart and arranged in the silicon island, and the gate electrode is located in the insulating layer and between the source electrode and the drain electrode;

[0013] A heat-insulating chamber is processed on the substrate, wherein the silicon island is spaced apart from the substrate;

[0014] forming an interdigitation sensitive electrode on the insulating layer;

[0015] forming a gas-sensitive layer for detecting the content of a sensitive gas on the interdigitated sensitive electrode to form a semi-finished product;

[0016] The semi-finished product is annealed and cooled to form a FET-heated interdigitated gas sensor.

[0017] As a preferred solution of a method for processing a FET-heated interdigital gas sensor, the gate is a polysilicon electrode. When forming the polysilicon electrode, the method includes:

[0018] forming a first sub-insulating layer on the silicon island and the substrate;

[0019] forming a polysilicon layer on the first sub-insulating layer;

[0020] forming a first stopping layer on the polysilicon layer;

[0021] patterning the first stopper layer to form an etching opening;

[0022] etching the polysilicon layer facing the etching opening;

[0023] The patterned first stopping layer is removed, and the remaining polysilicon layer forms the polysilicon electrode.

[0024] As a preferred solution of a method for processing a FET-heated interdigital gas sensor, when forming the interdigital sensitive electrode in the insulating layer, the method includes:

[0025] 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 constitute an insulating layer;

[0026] forming a second stopping layer on the insulating layer;

[0027] patterning the second stopper layer to form a filling opening;

[0028] etching the insulating layer opposite to the filling opening to form an electrode groove;

[0029] sputtering or chemical vapor depositing a conductive material into the electrode groove;

[0030] The patterned second stop layer is removed, and the conductive material filled in the electrode groove forms the interdigitation sensitive electrode.

[0031] As a preferred solution for the processing method of a FET-heated interdigital gas sensor, the gas-sensitive material is drop-coated on the interdigital sensitive electrode by screen printing, or the gas-sensitive material is formed on the interdigital sensitive electrode by evaporation to form the gas-sensitive layer.

[0032] As a preferred solution for the processing method of a FET-heated interdigital 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.

[0033] The beneficial effects of the present invention are:

[0034] The FET-heated interdigital gas sensor disclosed in the present invention integrates a FET heating component and an interdigital sensitive electrode, has a simple structure, and is conducive to the mass production of gas sensors. The Joule heat of the field-effect transistor of the FET heating component is used to heat the gas-sensitive layer, which makes the heating more uniform and can reduce system power consumption. Since it does not contain metal atoms, the problem of metal atom migration will not occur during the heating process, which increases the stability of the FET-heated interdigital gas sensor, reduces the probability of membrane cracks in the FET-heated interdigital gas sensor, and promotes the miniaturization and integration of the FET-heated interdigital gas sensor.

[0035] The processing method of the FET-heated interdigital gas sensor disclosed in the present invention has a simple process and is conducive to the mass production of gas sensors. The processed FET-heated interdigital gas sensor has the characteristics of uniform heating, low power consumption and long service life, which is conducive to the miniaturization and integrated design of the FET-heated interdigital gas sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in describing the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the contents of the embodiments of the present invention and these drawings without any creative work.

[0037] Figure 1 is a cross-sectional view of a FET-heated interdigital gas sensor provided by a specific embodiment of the present invention;

[0038] Figure 2 1 is a top view of a FET heating assembly of a FET-heated interdigital gas sensor provided by a specific embodiment of the present invention;

[0039] Figure 3 1 is a top view of an interdigital sensitive electrode of an interdigital gas sensor with FET heating provided by a specific embodiment of the present invention;

[0040] Figure 4 1 is a top view of the insulating layer of the FET-heated interdigital gas sensor provided by a specific embodiment of the present invention;

[0041] Figure 5 is a cross-sectional view of a FET-heated interdigital gas sensor according to a first alternative embodiment of the present invention;

[0042] Figure 6 is a cross-sectional view of a FET-heated interdigital gas sensor according to a second alternative embodiment of the present invention;

[0043] Figure 7 This is a flow chart of a method for processing a FET-heated interdigital gas sensor provided by a specific embodiment of the present invention;

[0044] Figures 8 to 24 It is a process diagram of a method for manufacturing a FET-heated interdigital gas sensor provided by a specific embodiment of the present invention.

[0045] In the picture:

[0046] 1. Substrate; 10. Thermal insulation chamber; 11. Silicon island;

[0047] 2. Insulation layer; 20. Electrode groove; 201. First sub-insulation layer; 202. Second sub-insulation layer; 21. Insulation layer body; 22. Connecting layer;

[0048] 3. FET heating component; 31. source; 32. drain; 33. gate; 330. polysilicon layer;

[0049] 4. Insert finger sensitive electrode;

[0050] 5. Gas sensitive layer;

[0051] 61. First stop layer; 610. Etching opening; 62. Second stop layer; 620. Filling opening;

[0052] 71. First photoresist layer; 710. First opening region; 72. Second photoresist layer; 720. Second opening region; 73. Protective layer; 74. Hard mask; 740. Thermal insulation hole; 75. Third photoresist layer; 750. Third opening region. DETAILED DESCRIPTION

[0053] To make the technical problems solved, the technical solutions adopted, and the technical effects achieved by the present invention more clearly understood, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. It is apparent that the described embodiments are only some of the embodiments of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0054] In the description of the present invention, it should be noted that the terms "center," "up," "down," "left," "right," "vertical," "horizontal," "inside," and "outside" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions.

[0055] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed or detachable connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention.

[0056] This embodiment provides a FET-heated interdigital gas sensor, such as Figure 1 and Figure 2As shown, it includes a substrate 1, an insulating layer 2, a FET heating component 3, an interdigital sensitive electrode 4 and a gas-sensitive layer 5. An insulating chamber 10 is provided on the substrate 1, and a silicon island 11 is provided in the insulating chamber 10. The silicon island 11 is spaced apart from the substrate 1, and the insulating layer 2 is provided on the same side of the silicon island 11 and the substrate 1. The FET heating component 3 includes a source 31, a gate 33 and a drain 32. The source 31 and the drain 32 are spaced apart and formed in the silicon island 11. The gate 33 is located in the insulating layer 2. The gate 33 is located between the source 31 and the drain 32. The source 31 and the drain 32 can generate heat when they are turned on. The interdigital sensitive electrode 4 is formed on the insulating layer 2. The gas-sensitive layer 5 covers the interdigital sensitive electrode 4. The resistivity change of the gas-sensitive layer 5 can be output through the interdigital sensitive electrode 4.

[0057] The FET-heated interdigital gas sensor provided in this embodiment integrates a FET heating component 3 and an interdigital sensitive electrode 4, has a simple structure, and is conducive to the mass production of gas sensors. The Joule heat of the field-effect transistor of the FET heating component 3 is used to heat the gas-sensitive layer 5, and the heating is more uniform, which can reduce the power consumption of the system. Since it does not contain metal atoms, there will be no problem of metal atom migration during the heating process, which increases the stability of the FET-heated interdigital gas sensor, reduces the probability of membrane cracks in the FET-heated interdigital gas sensor, and promotes the miniaturization and integration of the FET-heated interdigital gas sensor.

[0058] like Figure 2 As shown, the source 31 and drain 32 of this embodiment are both shaped as annular regular octagons, the number of each of the source 31 and drain 32 is one, and the source 31 and drain 32 are spaced apart and distributed on the silicon island 11. In other embodiments, the source 31 and drain 32 may also be circular or other annular polygons, the number of each of the source 31 and drain 32 may be two or more, or the number of the source 31 may be one more than the number of the drain 32, depending on actual needs.

[0059] like Figure 3 As shown, the interdigitated sensitive electrode 4 of this embodiment is a platinum electrode, a gold electrode or a titanium nitride electrode. The interdigitated sensitive electrode 4 serves as the sensing electrode of the gas-sensitive layer 5 and can sense the change in the resistivity of the gas-sensitive layer 5, thereby detecting the gas concentration of the sensitive gas. The electrode width and electrode gap of the interdigitated sensitive electrode 4 are not limited in this embodiment. In other embodiments, the interdigitated sensitive electrode 4 can also be made of other materials, which are selected according to actual needs. The cross-sectional area of ​​each tooth electrode of the interdigitated sensitive electrode 4 of this embodiment is much smaller than the cross-sectional area of ​​the source 31. The interdigitated sensitive electrode 4 of this structure has a larger unit area and can more effectively sense the gas-sensitive layer 5. In other embodiments, the cross-sectional area of ​​each tooth electrode of the interdigitated sensitive electrode 4 can also be designed to be similar to or the same as the cross-sectional area of ​​the source 31, which is set according to actual needs.

[0060] like Figure 1 As shown, the sidewalls of the heat-insulating chamber 10 of this embodiment extend along the axial direction of the substrate 1. This heat-insulating chamber 10 is processed by a dry deep silicon etching process. In other embodiments of the present invention, the sidewalls of the heat-insulating chamber 10 can also be arranged at an angle to the axial direction of the substrate 1, such as Figure 5 As shown, the heat-insulating chamber 10 is manufactured by a wet etching process.

[0061] like Figure 4 As shown, the insulating layer 2 of this embodiment includes an insulating layer body 21 and a connecting layer 22. The connecting layer 22 extends outward along one end of the insulating layer body 21, and the extension line of the connecting layer 22 passes through the center of the insulating layer body 21. In this embodiment, the insulating layer body 21 is square, and there are four connecting layers 22. Each connecting layer 22 is located at a corner of the insulating layer body 21. The angle between each connecting layer 22 and the long side and the wide side of the insulating layer body 21 is 135°. Compared with the structure in which the connecting layer 22 extends along one side of the insulating layer body 21, this structure increases the effective area of ​​the insulating layer 2, improves the robustness of the FET-heated interdigital gas sensor, and extends the service life of the FET-heated interdigital gas sensor. The source 31 and the drain 32 are wrapped between the insulating layer 2 and the silicon island 11, and the silicon island 11 does not contact the substrate 1, thereby avoiding leakage when the source 31 and the drain 32 are turned 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 may be specifically configured according to actual needs.

[0062] The gate 33 of this embodiment is formed between the silicon island 11 and the insulating layer 2 and is a polycrystalline silicon electrode. Conventional heating coils made of platinum can experience migration of platinum atoms at high temperatures, hindering heating and causing cracks in the coil, which can affect the proper functioning of the gas sensor. However, the gate 33 of this embodiment, made of polycrystalline silicon, does not exhibit these issues.

[0063] The FET heating component 3 of the FET-heated interdigital gas sensor of this embodiment can heat the gas-sensitive layer 5 to different temperatures under different heating voltages. Experiments have shown that the FET heating component 3 can heat the gas-sensitive layer 5 to a temperature of up to or even higher than 350°C, and the temperature of the gas-sensitive layer 5 is basically linearly correlated with the heating voltage.

[0064] It should be noted that, in other embodiments of the present invention, the heat-insulating chamber 10 may be formed on the side of the substrate 1 where the insulating layer 2 is provided, and the heat-insulating chamber 10 may be formed by wet etching, such as Figure 6 shown.

[0065] This embodiment also provides a method for processing the interdigital gas sensor suitable for the above FET heating, such as Figure 7 As shown, including:

[0066] S1. Provide a substrate 1, and implant ions into a local area of ​​the substrate 1 to form a silicon island 11.

[0067] Specifically, the substrate 1 of this embodiment is P-type silicon, and S1 includes the following steps:

[0068] S11, coating a photoresist on the upper surface of the substrate 1 to form a first photoresist layer 71;

[0069] S12, patterning the first photoresist layer 71, forming a first opening area 710 on the first photoresist layer 71;

[0070] S13, phosphorus ions are doped into the substrate 1 through the first opening area 710, and the portion of the substrate 1 doped with phosphorus ions becomes an N-well silicon island. Figure 8 As shown;

[0071] S14, removing the patterned first photoresist layer 71, as shown in FIG. Figure 9 shown.

[0072] Specifically, the shape of the N-well silicon island in this embodiment is a square. In other embodiments, the shape of the N-well silicon island can also be a rectangle, a circle, or other polygons, which is selected according to actual needs.

[0073] S2 . Form a source 31 and a drain 32 on the silicon island 11 . The source 31 and the drain 32 are arranged in the silicon island 11 at intervals.

[0074] Specifically, when forming the source 31 and the drain 32, S2 includes the following steps:

[0075] S21, coating photoresist on the upper surface of the substrate 1 and the silicon island 11 to form a second photoresist layer 72;

[0076] S22, patterning the second photoresist layer 72, forming a second opening area 720 on the second photoresist layer 72, as shown in FIG. Figure 10 As shown;

[0077] S23, boron ions are doped into the silicon island 11 through the second opening area 720, and the portion of the silicon island 11 doped with boron ions becomes the source 31 and the drain 32. Figure 11 As shown;

[0078] S24, removing the patterned second photoresist layer 72, as shown in FIG. Figure 12 shown.

[0079] Specifically, the processed source electrode 31 and drain electrode 32 are both in the shape of an annular regular octagon, the number of the source electrode 31 and the number of the drain electrode 32 are both one, and the source electrode 31 and the drain electrode 32 are spaced apart and distributed on the silicon island 11. In other embodiments, the shape of the source electrode 31 and the drain electrode 32 can also be circular or other annular polygons, the number of the source electrode 31 and the drain electrode 32 can be two or more, or the number of the source electrode 31 can be one more than the number of the drain electrode 32, according to actual needs.

[0080] S3 . Form an insulating layer 2 and a gate 33 on the silicon island 11 . The gate 33 is located in the insulating layer 2 and between the source 31 and the drain 32 .

[0081] In this embodiment, the gate 33 is a polysilicon electrode, and S3 includes the following steps:

[0082] 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. Figure 13 As shown;

[0083] S32, forming a first stopping layer 61 on the polysilicon layer 330;

[0084] S33, patterning the first stopper layer 61 to form an etching opening 610, as shown in FIG. Figure 14 As shown;

[0085] S34, etching the polysilicon layer 330 facing the etching opening 610, as shown in FIG. Figure 15 As shown;

[0086] S35, removing the patterned first stopper layer 61, and the remaining polysilicon layer 330 forms a polysilicon electrode, such as Figure 16 As shown;

[0087] 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, the first sub-insulating layer 201 and the second sub-insulating layer 202 forming an insulating layer 2, such as Figure 17 shown.

[0088] In this embodiment, the first stopping layer 61 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 can also be linear, circular, or other circular polygonal shapes, depending on actual needs.

[0089] Specifically, the insulating layer 2 is formed by a chemical vapor deposition process. In this embodiment, the insulating layer 2 is a silicon oxide layer. In other embodiments, the insulating layer 2 may be a single-layer structure formed of an insulating material such as silicon nitride or aluminum oxide, or a structure of at least two layers formed of an insulating material such as silicon oxide, silicon nitride, or aluminum oxide, depending on actual needs.

[0090] S4 , forming an interdigitating sensitive electrode 4 on the insulating layer 2 .

[0091] When forming the interdigitation sensitive electrode 4 on the insulating layer 2, S4 includes the following steps:

[0092] S41, forming a second stopping layer 62 on the insulating layer 2;

[0093] S42, patterning the second stopping layer 62 to form a filling opening 620;

[0094] S43, etching the insulating layer 2 opposite to the filling opening 620 to form the electrode groove 20, as shown in FIG. Figure 18 As shown;

[0095] S44, sputtering or chemical vapor deposition of a conductive material into the electrode groove 20;

[0096] S45, remove the patterned second stop layer 62, and fill the conductive material in the electrode groove 20 to form the interdigital sensitive electrode 4, as shown in FIG. Figure 19 shown.

[0097] The second stop layer 62 of this embodiment is a photoresist layer. The structure of the finger sensitive electrode 4 in step S45 is as follows. Figure 3 As shown, the interdigitated sensitive electrode 4 of this structure can be sensitive to the change in the resistivity of the gas sensitive layer 5, thereby detecting the concentration of the sensitive gas. The interdigitated sensitive electrode 4 is a platinum electrode, a gold electrode, or a titanium nitride electrode, or is made of other conductive materials, which is not specifically limited in this embodiment.

[0098] S5, forming a gas-sensitive layer 5 for detecting the content of sensitive gas on the interdigitated sensitive electrode 4, such as Figure 20 shown.

[0099] The gas sensitive material is drop-coated on the interdigital sensitive electrode 4 by screen printing, or is formed on the interdigital sensitive electrode 4 by evaporation to form a gas sensitive layer 5 in the shape of a water drop.

[0100] Specifically, the gas-sensitive material of the gas-sensitive layer 5 of this embodiment is tin dioxide, tungsten trioxide or zinc oxide, and the precious metal contained in the gas-sensitive layer 5 may be platinum, gold, palladium, rhodium or iridium with catalytic effect. The precious metal can reduce the semiconductor barrier of tin dioxide, tungsten trioxide or zinc oxide, and promote the selectivity of the FET heated interdigital gas sensor.

[0101] Of course, in other embodiments of the present invention, the gas-sensitive material may be formed on the interdigitated sensitive electrode 4 by an evaporation method or an inkjet printing method to form the gas-sensitive layer 5. In this case, S5 includes the following steps:

[0102] S51, coating a fourth photoresist layer on the insulating layer 2 and the interdigitation sensitive electrode 4;

[0103] S52, patterning the fourth photoresist layer to form a fourth opening area;

[0104] S53, forming a gas-sensitive material on the interdigitated sensitive electrode 4 by using an evaporation method in the fourth opening area to form a gas-sensitive layer 5;

[0105] S54, removing the patterned fourth photoresist layer.

[0106] 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. Figure 21 As shown, damage to the gas-sensitive layer 5 is avoided during processing of the heat-insulating chamber 10 .

[0107] S6. A heat-insulating chamber 10 is processed at one end of the substrate 1 away from the insulating layer 2 to form a semi-finished product.

[0108] Specifically, when processing the heat-insulating chamber 10, S6 includes the following steps:

[0109] S61, chemically depositing an insulating material on the substrate 1 to form a hard mask 74;

[0110] S62, coating a third photoresist layer 75 on the hard mask 74;

[0111] S63, patterning the third photoresist layer 75 to form a third opening area 750;

[0112] S64, etching the hard mask 74 facing the third opening area 750 to form a thermal insulation hole 740, such as Figure 22 As shown;

[0113] S65, deep silicon etching the substrate 1 facing the thermal insulation hole 740 to form a thermal insulation chamber 10, such as Figure 23 As shown;

[0114] S66, remove the patterned third photoresist layer 75 and the hard mask 74, and remove the protective layer 73, as shown in FIG. Figure 24 shown.

[0115] The dry etching process in step S65 has the advantages of both anisotropy and good selectivity. Compared with wet etching, it has low cost but slow etching rate. Of course, in other embodiments of the present invention, a wet self-stop etching process can also be used to form the thermal insulation chamber 10. For example, a potassium hydroxide solution or a tetramethylammonium hydroxide solution is used to wet-etch the substrate 1. Since the concentration of phosphorus ions in the silicon islands 11 is higher than the concentration of boron ions in the substrate 1, the etching rate of the etching solution on the substrate 1 with low ion concentration is much higher than the etching rate of the silicon islands 11, thereby showing a self-stop effect, a fast etching rate, simple equipment, and high mechanical sensitivity. In actual processing, the processing technology can be selected according to actual needs.

[0116] S7, annealing and cooling the semi-finished product to form a FET-heated interdigital gas sensor.

[0117] The semi-finished product in this step refers to a semi-finished product of a single FET-heated interdigital gas sensor. After annealing, the gas-sensing layer 5 of the FET-heated interdigital gas sensor has a porous shape, and exhibits higher linearity and sensitivity than a process without annealing and cooling. The annealing temperature and duration are commonly used techniques in the art and can be adjusted by those skilled in the art based on practical needs. This embodiment does not impose specific limitations thereon.

[0118] The processing method of the FET-heated interdigital gas sensor provided in this embodiment has a simple process and is conducive to the mass production of gas sensors. The processed FET-heated interdigital gas sensor has the characteristics of uniform heating, low power consumption and long life, which is conducive to the miniaturization and integrated design of the FET-heated interdigital gas sensor.

[0119] In order to process the insulating layer 2 into Figure 4 To obtain the shape shown in FIG. 1 , the insulating layer 2 needs to be etched. Specifically, after the insulating layer 2 is formed and before the gas-sensitive 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 area. The insulating layer 2 facing the fifth opening area is etched so that the insulating layer 2 is formed as shown in FIG. Figure 4 In other embodiments, the processing steps of the insulating layer 2 may be to form a sixth photoresist layer on the substrate 1, the insulating layer 2 and the silicon island 11 after the insulating chamber 10 is formed and before the protective layer 73 is removed, pattern the sixth photoresist layer to form a sixth opening area, and etch the insulating layer 2 facing the sixth opening area so that the insulating layer 2 is formed as shown. Figure 4 The shape shown is formed, and finally the sixth photoresist layer is removed.

[0120] Processing Figure 6In the FET-heated interdigital gas sensor shown, the thermal insulation chamber 10 is formed by wet etching after the insulating layer 2 is formed. In order to reduce the impact on the gas-sensitive layer 5, this step is implemented before the gas-sensitive layer 5 is formed. This embodiment does not make specific limitations.

[0121] It should be noted that, in other embodiments of the present invention, the gate electrode 33 may be processed first, and then the source electrode 31 and the drain electrode 32 may be processed, and the specific method is selected according to actual needs.

[0122] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the concept of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A FET-heated interdigital gas sensor, characterized in that: include: A substrate, on which a heat-insulating chamber is provided, wherein a silicon island is provided in the heat-insulating chamber, and the silicon island is spaced apart from the substrate; an insulating layer, disposed on the same side of the silicon island and the substrate; A FET heating component, comprising a source electrode, a gate electrode, and a drain electrode, wherein the source electrode and the drain electrode are spaced apart and formed in the silicon island, the gate electrode is located in the insulating layer and between the source electrode and the drain electrode, and the source electrode and the drain electrode can generate heat when they are turned on; Interdigital sensitive electrodes are formed on the insulating layer; A gas-sensitive layer covering the interdigital sensitive electrode, wherein a resistivity change of the gas-sensitive layer can be outputted through the interdigital sensitive electrode; The insulating layer includes an insulating layer body and a connecting layer, the connecting layer extends outward along one end of the insulating layer body, the extension line of the connecting layer passes through the center of the insulating layer body, the insulating layer body is square, the number of the connecting layers is four, each of the connecting layers is located at a corner of the insulating layer body, and the angle between each connecting layer and the long side and wide side of the insulating layer body is 135°.

2. The FET-heated interdigital gas sensor according to claim 1, characterized in that: The interdigital sensitive electrode is a platinum electrode, a gold electrode or a titanium nitride electrode.

3. The FET-heated interdigital gas sensor according to claim 1, characterized in that: The sidewall of the heat-insulating chamber extends along the axial direction of the substrate, or the sidewall of the heat-insulating chamber is arranged at an angle to the axial direction of the substrate.

4. The FET-heated interdigital gas sensor according to claim 1, wherein: The insulating layer includes an insulating layer body and a connecting layer. The connecting layer extends outward along one end of the insulating layer body, and an extension line of the connecting layer passes through the center of the insulating layer body.

5. The FET-heated interdigital gas sensor according to claim 1, characterized in that: The gate is formed between the silicon island and the insulating layer and is a polysilicon electrode.

6. A method for processing a FET-heated interdigital gas sensor according to any one of claims 1 to 5, characterized in that: include: providing a substrate, and implanting ions into a local region of the substrate to form a silicon island; forming an insulating layer, a source electrode, a drain electrode, and a gate electrode on the silicon island, wherein the source electrode and the drain electrode are spaced apart and arranged in the silicon island, and the gate electrode is located in the insulating layer and between the source electrode and the drain electrode; A heat-insulating chamber is processed on the substrate, wherein the silicon island is spaced apart from the substrate; forming an interdigitation sensitive electrode on the insulating layer; forming a gas-sensitive layer for detecting the content of a sensitive gas on the interdigitated sensitive electrode to form a semi-finished product; The semi-finished product is annealed and cooled to form a FET-heated interdigitated gas sensor.

7. The method for processing the FET-heated interdigital gas sensor according to claim 6, characterized in that: The gate is a polysilicon electrode, and forming 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 stopping layer on the polysilicon layer; patterning the first stopper layer to form an etching opening; etching the polysilicon layer facing the etching opening; The patterned first stopping layer is removed, and the remaining polysilicon layer forms the polysilicon electrode.

8. The method for processing the FET-heated interdigital gas sensor according to claim 7, wherein: When forming the interdigitation sensitive electrode 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 constitute an insulating layer; forming a second stopping layer on the insulating layer; patterning the second stopper layer to form a filling opening; etching the insulating layer opposite to the filling opening to form an electrode groove; sputtering or chemical vapor depositing a conductive material into the electrode groove; The patterned second stop layer is removed, and the conductive material filled in the electrode groove forms the interdigitation sensitive electrode.

9. The method for processing the FET-heated interdigital gas sensor according to claim 6, wherein: The gas-sensitive material is drop-coated on the interdigital sensitive electrode by a screen printing method, or the gas-sensitive material is formed on the interdigital sensitive electrode by an evaporation method to form the gas-sensitive layer.

10. The method for processing the FET-heated interdigital gas sensor according to claim 6, characterized in that: 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.

Images