A flow gas integrated sensor and manufacturing method thereof

Abstract

The present invention provides a flow gas integrated sensor and a manufacturing method thereof, which includes: a substrate, a silicon deep groove is provided on the substrate; a suspension bridge, an arbitrary suspension bridge is arranged above the silicon deep groove and connected to the substrate; a temperature sensitive unit is connected to the suspension bridge, and a gas sensitive unit is connected to the suspension bridge, which includes an insulating layer, a metal interdigital electrode and a gas sensitive material layer connected in sequence, wherein the insulating layer is connected to the suspension bridge. The present invention integrates the temperature sensitive unit and the gas sensitive unit on the same substrate through the suspension bridge, which can realize simultaneous detection of flow and gas on a single chip, thereby making it have the advantages of miniaturization, integration and low power consumption, and can reduce the back-end bonding and packaging process, thereby achieving the purpose of reducing costs and increasing efficiency. Compared with the conventional integration methods and structures at this stage, the present application does not need to be packaged and electrically connected by bonding, thereby having significant advantages such as simple processing, wide application range, stable structure and high integration.

Description

Technical Field

[0001] The present invention relates to the technical field of MEMS integrated sensors, and in particular to a flow gas integrated sensor and a manufacturing method thereof. Background Art

[0002] In key areas such as air purification and medical testing, there is a growing demand for real-time monitoring of gas composition and accurate measurement of gas flow. To meet this demand, traditional technical solutions usually use two independent sensors installed in the airway - MEMS gas sensor and MEMS flow sensor. These two sensors each achieve their functions based on different working principles.

[0003] MEMS flow sensors utilize the characteristics of temperature-sensitive materials. When air flows through the surface of these materials, it causes temperature changes, which can be sensed by the sensor and converted into electrical signals, thereby quantifying the flow rate of the fluid. The advantage of this method is that it can measure gas flow more accurately, but it also has certain limitations, such as sensitivity to temperature changes may lead to errors in measurement results.

[0004] MEMS gas sensors, on the other hand, coat a micro hot plate with a material that is sensitive to a specific gas. When gas molecules come into contact with these sensitive materials, a redox reaction occurs, causing the material's resistance to change. By detecting the change in resistance, specific components in the gas can be identified and quantified. This approach has high sensitivity and selectivity in gas detection, but it also faces challenges in response time and stability.

[0005] In order to adapt to the trend of sensor miniaturization, technological progress has promoted the integration of the two chips in a package shell through wire bonding technology, which has reduced the overall volume to a certain extent, saved space, and improved system integration. However, this integrated packaging technology still faces some difficult-to-overcome problems: first, the volume is still large, which is not conducive to further miniaturization and the development of portable devices; second, the power consumption is high, which is not conducive to long-term operation of equipment; and finally, the high cost limits its popularity in large-scale applications.

[0006] Therefore, existing technical solutions still have much room for improvement in the pursuit of higher performance, smaller size, lower power consumption and more economical sensor integration. Summary of the invention

[0007] To this end, the technical problem to be solved by the present invention is to overcome the problems of large volume, high power consumption and high cost of sensor integrated packaging in the prior art, and to provide a flow gas integrated sensor and a manufacturing method thereof.

[0008] In order to solve the above technical problems, the present invention provides a flow gas integrated sensor, which includes: a substrate, on which a silicon deep trench is provided; at least two suspension bridges, any of which is arranged above the silicon deep trench and connected to the substrate; at least one temperature sensitive unit, which is connected to the suspension bridge, and at least one gas sensitive unit, which is connected to the suspension bridge, and includes an insulating layer, a metal interdigitated electrode and a gas sensitive material layer connected in sequence, wherein the insulating layer is connected to the suspension bridge.

[0009] In one embodiment of the present invention, the flow gas integrated sensor includes three suspension bridges, which are evenly spaced along the width direction of the silicon deep groove, wherein the suspension bridges on both sides are respectively connected to one of the temperature sensitive units, and the suspension bridge in the middle is connected to the gas sensitive unit.

[0010] In one embodiment of the present invention, the substrate thickness is 200-1000 μm and the crystal orientation is <100> , with a side length of 1000~5000μm; the temperature sensitive unit extends in the same direction as the suspension bridge, and the width of the temperature sensitive unit is 60%~80% of the corresponding width of the suspension bridge.

[0011] In one embodiment of the present invention, the silicon deep groove is located at the center of the silicon substrate, which is an inverted trapezoidal groove or a vertical groove, and its opening shape on the upper surface of the substrate is configured as one of a square, a rectangle or a rhombus. The side length of the silicon deep groove is 200~3000μm, and its depth in the thickness direction of the substrate is 50~500μm.

[0012] In one embodiment of the present invention, the suspension bridge is configured as a double-ended dielectric film, whose substrate includes one or both of silicon dioxide and silicon nitride, and has a thickness of 100-2000 nm, a length of 200-3000 μm, and a width of 10-200 μm.

[0013] In one embodiment of the present invention, the flow gas integrated sensor also includes at least one heating unit, which is correspondingly arranged between the suspension bridge and the gas sensitive unit, the heating unit and the suspension bridge extend in the same direction, and the width of the heating unit is 60%~80% of the corresponding width of the suspension bridge; the heating unit and the temperature sensitive unit are both configured as metal materials or polysilicon materials, and the thickness is 100~6000nm, wherein the metal materials include chromium, titanium, platinum, nickel, and gold, and the polysilicon material includes N-type or P-type doped polysilicon.

[0014] In one embodiment of the present invention, the insulating layer includes one or both of silicon dioxide or silicon nitride, and the thickness thereof is 100~2000nm; the metal interdigitated electrode includes one of chromium, titanium, platinum, nickel, and gold, and the thickness thereof is 100~6000nm; the gas sensitive material includes one of tin oxide, indium oxide, or tungsten oxide, and the thickness thereof is 1000~5000nm.

[0015] In one embodiment of the present invention, the flow gas integrated sensor further includes at least eight pads, which are disposed on the substrate and are electrically connected to external electronic components.

[0016] The present invention also provides a method for manufacturing a flow gas integrated sensor, which is used to prepare the above-mentioned flow gas integrated sensor, and comprises: step S1, preparing a suspension bridge on a clean substrate: depositing a dielectric film on the substrate and then spin-coating a photoresist, and after photolithography development and patterning, dry etching the dielectric film to form a suspension bridge; step S2, preparing a temperature sensitive unit and a gas sensitive unit on the suspension bridge; wherein the preparation of the temperature sensitive unit is specifically: adopting magnetron sputtering or evaporating a metal layer and then spin-coating a photoresist, and after photolithography development and patterning, etching the metal layer to form the temperature sensitive unit; preparing the gas The body sensitive unit is specifically as follows: a. Spin-coating photoresist after plasma enhanced chemical vapor deposition of silicon oxide or silicon nitride, and forming an insulating layer by reactive ion dry etching after photolithography development and patterning; b. Spin-coating photoresist after magnetron sputtering or evaporation of a metal layer on the insulating layer, and forming metal finger electrodes by dry or wet etching of the metal layer after photolithography development and patterning; c. Depositing a gas sensitive material layer on the metal finger by screen printing to complete the preparation of the gas sensitive unit; step S3, etching a silicon deep groove on the substrate to obtain a flow gas integrated sensor.

[0017] In one embodiment of the present invention, step S1 is specifically as follows: after cleaning and drying the substrate to be processed, a silicon dioxide dielectric film is deposited on its surface by a thermal oxidation process, or a silicon nitride dielectric film is deposited on its surface by a plasma enhanced chemical vapor process, so that the dielectric film thickness is 100~2000nm, and photoresist is spin-coated and after photolithography development and patterning, reactive ion dry etching is used to form the suspension bridge; step S3 is specifically as follows: spin-coating photoresist on the substrate and after photolithography development and patterning, KOH or TMAH is used to wet-etch silicon deep grooves, and the flow gas integrated sensor is obtained after degumming.

[0018] The above technical solution of the present invention has the following advantages compared with the prior art: The flow gas integrated sensor and its manufacturing method described in the present invention integrate the temperature sensitive unit and the gas sensitive unit on the same substrate through a suspension bridge, which can realize the simultaneous detection of flow and gas on a single chip, thereby making it have the advantages of miniaturization, integration and low power consumption, and can also reduce the back-end bonding and packaging process, thereby achieving the purpose of reducing costs and increasing efficiency. Compared with the conventional integration methods and structures at this stage, the present application does not need to be packaged and electrically connected by bonding, thus having the significant advantages of simple processing, wide application range, stable structure and high integration, and has broad prospects for use in this industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0020] Figure 1 It is a schematic diagram of the planar structure of the flow gas integrated sensor in the preferred embodiment of the present invention; Figure 2 yes Figure 1 Schematic diagram of the structure of the flow gas integrated sensor layer shown; Figure 3 is a schematic diagram of the planar structure of a flow gas integrated sensor in another embodiment of the present invention; Figure 4 yes Figure 3 Schematic diagram of the flow gas integrated sensor layer structure shown.

[0021] Explanation of the reference numerals in the specification: 100, substrate; 101, silicon deep trench; 102, suspension bridge; 103, temperature sensitive unit; 104, heating unit; 105, gas sensitive unit; 105a, insulating layer; 105b, metal interdigitated electrode; 105c, gas sensitive material layer; 106, pad. DETAILED DESCRIPTION

[0022] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention. Embodiment 1

[0023] See also Figure 1 and Figure 2As shown, this embodiment provides a flow gas integrated sensor, which includes: a substrate 100, on which a silicon deep trench 101 is provided; at least two suspension bridges 102, any of which is arranged above the silicon deep trench 101 and connected to the substrate 100; at least one temperature sensitive unit 103, which is connected to the suspension bridge 102, and at least one gas sensitive unit 105, which is connected to the suspension bridge 102, and includes an insulating layer 105a, a metal interdigitated electrode 105b and a gas sensitive material layer 105c connected in sequence, wherein the insulating layer 105a is connected to the suspension bridge 102.

[0024] The flow gas integrated sensor described in this embodiment integrates the temperature sensitive unit 103 and the gas sensitive unit 105 on the same substrate 100 through the suspension bridge 102, which can realize the simultaneous detection of flow and gas on a chip, thereby making it have the advantages of miniaturization, integration and low power consumption, and at the same time can reduce the back-end bonding packaging process, thereby achieving the purpose of reducing costs and increasing efficiency. Compared with the conventional integration methods and structures at this stage, this application does not need to be packaged and electrically connected by bonding, thus having the significant advantages of simple processing, wide application range, stable structure and high integration, and has broad application prospects in this industry.

[0025] In this embodiment, the substrate 100 has a thickness of 500 μm and a crystal orientation of <100> , with a side length of 1000μm; an inverted trapezoidal silicon deep trench 101 is provided in the center, and its opening shape on the upper surface of the substrate 100 is configured as a square, the side length of the silicon deep trench 101 is 500μm, and the depth in the thickness direction of the substrate 100 is 120μm.

[0026] Further, the flow gas integrated sensor in this embodiment includes three suspension bridges 102, which are evenly spaced and arranged on the silicon deep groove 101 along the width direction thereof, wherein the suspension bridges 102 located on both sides are respectively connected to one of the temperature sensitive units 103, and the suspension bridge 102 located in the middle is connected to the gas sensitive unit 105. Specifically, the suspension bridge 102 in this embodiment is configured as a double-end fixed dielectric film, whose substrate includes silicon dioxide, and whose thickness is 200nm, length is 500μm, and width is 100μm.

[0027] In this embodiment, two temperature sensitive units 103 are provided, which are used for temperature detection respectively. The temperature sensitive units 103 extend in the same direction as the suspension bridge 102, and the width of the temperature sensitive unit 103 is 80% of the width of the corresponding suspension bridge 102, thereby ensuring the connection stability and improving the detection range. In different implementations, the width of the temperature sensitive unit 103 can be configured to be 60% to 80% of the width of the corresponding suspension bridge 102.

[0028] Further, see Figure 1 and Figure 2 As shown, the flow gas integrated sensor in this embodiment further includes a heating unit 104, which is correspondingly arranged between the suspension bridge 102 and the gas sensitive unit 105, and the heating unit 104 extends in the same direction as the suspension bridge 102, and the width of the heating unit 104 is 80% of the width of the corresponding suspension bridge 102. In different implementations, the width of the heating unit 104 can be configured to be 60% to 80% of the width of the corresponding suspension bridge 102. Further, the heating unit 104 and the temperature sensitive unit 103 are both configured to be metal materials or polysilicon materials, and the thickness is 100 to 6000 nm, wherein the metal materials include titanium and platinum.

[0029] In this embodiment, the insulating layer 105a includes one or both of silicon dioxide and silicon nitride, and the thickness thereof is 200nm; the metal interdigital electrode 105b includes titanium and gold, and the thickness thereof is 600nm; the gas sensitive material includes tin oxide, and the thickness thereof is 3000nm. In addition, the flow gas integrated sensor in this embodiment further includes at least eight pads 106, which are arranged on the substrate 100 and are electrically connected to external electronic components. Embodiment 2

[0030] See also Figure 3 and Figure 4As shown, this embodiment provides another structure of the flow gas integrated sensor, the operation process and principle of which are the same as those of the first embodiment, and will not be described in detail here. In this embodiment, the thickness of the substrate 100 is 5000 μm, and the crystal orientation is <100> , with a side length of 10005μm; the silicon deep groove 101 located at the center of the silicon substrate 100 is a vertical groove, and its opening shape on the upper surface of the substrate 100 is configured as one of the rhombuses, the side length of the silicon deep groove 101 is 500μm, and its depth in the thickness direction of the substrate 100 is 500μm. In different embodiments, the thickness of the substrate 100 can be configured to be 200~1000μm, and its side length can be configured to be 1000~5000μm. The opening shape of the silicon deep groove 101 on the upper surface of the substrate 100 can be configured as one of the square, rectangle or rhombus, the side length of the silicon deep groove 101 can be configured to be 200~3000μm, and its depth in the thickness direction of the substrate 100 can be configured to be 50~500μm.

[0031] In this embodiment, the suspension bridge 102 is configured as a double-end fixed dielectric film, whose substrate includes silicon nitride, and whose thickness is 600nm, length is 500μm, and width is 80μm. In different implementations, the suspension bridge 102 substrate may include one or both of silicon dioxide and silicon nitride, whose thickness can be configured to be 100-2000nm, length can be configured to be 200-3000μm, and width can be configured to be 10-200μm.

[0032] In this embodiment, the heating unit 104 and the temperature sensitive unit 103 can both be configured as polysilicon material, and the thickness is 600nm. In different implementations, the heating unit 104 and the temperature sensitive unit 103 can both be configured as metal material or polysilicon material, and the thickness can be configured to be 100~6000nm, wherein the metal material includes chromium, titanium, platinum, nickel, and gold, and the polysilicon material includes N-type or P-type doped polysilicon.

[0033] In this embodiment, the insulating layer 105a includes silicon nitride, and its thickness is 200nm; in different implementations, the insulating layer 105a may include one or both of silicon dioxide or silicon nitride, and its thickness can be configured to be 100~2000nm; the metal interdigitated electrode 105b includes one of chromium, titanium, platinum, nickel, and gold, and its thickness can be configured to be 100~6000nm; the gas sensitive material includes one of tin oxide, indium oxide or tungsten oxide, and its thickness can be configured to be 1000~5000nm. Embodiment 3

[0034] This embodiment provides a method for manufacturing a flow gas integrated sensor, which is used to prepare the flow gas integrated sensor described in Embodiment 1, and includes: Step S1, preparing a suspension bridge 102 on a clean substrate 100: after depositing a dielectric film on the substrate 100, spin-coating photoresist, and after photolithography development and patterning, dry etching the dielectric film to form the suspension bridge 102; further, in this embodiment, step S1 is specifically: after cleaning and drying the substrate 100 to be processed, a silicon dioxide dielectric film is deposited on its surface by a thermal oxidation process, or a silicon nitride dielectric film is deposited on its surface by a plasma enhanced chemical vapor process, so that the dielectric film thickness is 100~2000nm, spin coating photoresist and after photolithography development and patterning, reactive ion dry etching is used to form the suspension bridge 102.

[0035] Step S2, preparing a temperature sensitive unit 103 and a gas sensitive unit 105 on the suspension bridge 102; wherein, the preparation of the temperature sensitive unit 103 is specifically as follows: spin-coating a photoresist after magnetron sputtering or evaporating a metal layer, and etching the metal layer after photolithography development and patterning to form the temperature sensitive unit 103; the preparation of the gas sensitive unit 105 is specifically as follows: a, spin-coating a photoresist after plasma enhanced chemical vapor deposition of silicon oxide or silicon nitride, and forming an insulating layer 105a by reactive ion dry etching after photolithography development and patterning; b, spin-coating a photoresist after magnetron sputtering or evaporating a metal layer on the insulating layer 105a, and forming a metal interdigital electrode 105b by dry or wet etching the metal layer after photolithography development and patterning; c, depositing a gas sensitive material layer 105c on the metal interdigital by screen printing to complete the preparation of the gas sensitive unit 105; Step S3, etching a silicon deep groove 101 on the substrate 100 to obtain a flow gas integrated sensor. Furthermore, in this embodiment, step S3 is specifically: spin coating photoresist on the substrate 100 and after photolithography development and patterning, using KOH or TMAH to wet etch the silicon deep groove 101, and obtaining the flow gas integrated sensor after de-bonding.

[0036] In summary, the flow gas integrated sensor and its manufacturing method described in the present invention integrate the temperature sensitive unit 103 and the gas sensitive unit 105 on the same substrate 100 through the suspension bridge 102, which can realize the simultaneous detection of flow and gas on a chip, thereby making it have the advantages of miniaturization, integration and low power consumption, and at the same time can reduce the back-end bonding packaging process, thereby achieving the purpose of reducing costs and increasing efficiency. Compared with the conventional integration methods and structures at this stage, the present application does not need to be packaged and electrically connected by bonding, thus having the significant advantages of simple processing, wide application range, stable structure and high integration, and has broad application prospects in this industry.

[0037] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A flow gas integrated sensor, characterized in that: include: A substrate, wherein a silicon deep trench is provided on the substrate; at least two suspension bridges, any of which is disposed above the silicon deep trench and connected to the substrate; at least one temperature sensitive unit, wherein the temperature sensitive unit is connected to the suspension bridge, At least one gas sensitive unit is connected to the suspension bridge, and comprises an insulating layer, a metal interdigitated electrode and a gas sensitive material layer connected in sequence, wherein the insulating layer is connected to the suspension bridge.

2. The flow gas integrated sensor according to claim 1, characterized in that: The flow gas integrated sensor includes three suspension bridges which are evenly spaced and arranged on the silicon deep groove along its width direction, wherein the suspension bridges on both sides are respectively connected to one of the temperature sensitive units, and the suspension bridge in the middle is connected to the gas sensitive unit.

3. The flow gas integrated sensor according to claim 1, characterized in that: The substrate thickness is 200-1000 μm and the crystal orientation is <100> , with a side length of 1000~5000μm; the temperature sensitive unit extends in the same direction as the suspension bridge, and the width of the temperature sensitive unit is 60%~80% of the corresponding width of the suspension bridge.

4. The flow gas integrated sensor according to claim 1, characterized in that: The silicon deep groove is located at the center of the silicon substrate. It is an inverted trapezoidal groove or a vertical groove. The opening shape on the upper surface of the substrate is configured as one of a square, a rectangle or a rhombus. The side length of the silicon deep groove is 200~3000μm, and its depth in the thickness direction of the substrate is 50~500μm.

5. The flow gas integrated sensor according to claim 1, characterized in that: The suspension bridge is configured as a double-ended fixed dielectric film, the substrate of which includes one or both of silicon dioxide and silicon nitride, with a thickness of 100-2000 nm, a length of 200-3000 μm, and a width of 10-200 μm.

6. The flow gas integrated sensor according to claim 1, characterized in that: The flow gas integrated sensor also includes at least one heating unit, which is correspondingly arranged between the suspension bridge and the gas sensitive unit. The heating unit and the suspension bridge extend in the same direction, and the width of the heating unit is 60%~80% of the corresponding width of the suspension bridge; the heating unit and the temperature sensitive unit are both configured as metal materials or polysilicon materials, and the thickness is 100~6000nm, wherein the metal materials include chromium, titanium, platinum, nickel, and gold, and the polysilicon material includes N-type or P-type doped polysilicon.

7. The flow gas integrated sensor according to claim 1, characterized in that: The insulating layer includes one or both of silicon dioxide or silicon nitride, and the thickness thereof is 100-2000nm; the metal interdigitated electrode includes one of chromium, titanium, platinum, nickel, and gold, and the thickness thereof is 100-6000nm; the gas sensitive material includes one of tin oxide, indium oxide, or tungsten oxide, and the thickness thereof is 1000-5000nm.

8. The flow gas integrated sensor according to claim 1, characterized in that: The flow gas integrated sensor further includes at least eight pads, which are disposed on the substrate and are electrically connected to external electronic components.

9. A method for manufacturing a flow gas integrated sensor, characterized in that: A flow gas integrated sensor for preparing any one of claims 1 to 8, comprising: Step S1, preparing a suspension bridge on a clean substrate: depositing a dielectric film on the substrate and then spin-coating a photoresist, and after photolithography development and patterning, dry-etching the dielectric film to form a suspension bridge; Step S2, preparing a temperature sensitive unit and a gas sensitive unit on the suspension bridge; wherein the preparation of the temperature sensitive unit is specifically as follows: spin coating photoresist after magnetron sputtering or evaporation of a metal layer, and etching the metal layer after photolithography development and patterning to form a temperature sensitive unit; the preparation of the gas sensitive unit is specifically as follows: a, spin coating photoresist after plasma enhanced chemical vapor deposition of silicon oxide or silicon nitride, and forming an insulating layer by reactive ion dry etching after photolithography development and patterning; b, spin coating photoresist after magnetron sputtering or evaporation of a metal layer on the insulating layer, and forming a metal interdigital electrode by dry or wet etching of the metal layer after photolithography development and patterning; c, depositing a gas sensitive material layer on the metal interdigital by screen printing to complete the preparation of the gas sensitive unit; Step S3, etching a silicon deep groove on the substrate to obtain a flow gas integrated sensor.

10. The method for manufacturing a flow gas integrated sensor according to claim 9, characterized in that: Step S1 is specifically as follows: after cleaning and drying the substrate to be processed, a silicon dioxide dielectric film is deposited on its surface by a thermal oxidation process, or a silicon nitride dielectric film is deposited on its surface by a plasma enhanced chemical vapor process, so that the dielectric film thickness is 100-2000nm, and photoresist is spin-coated and after photolithography development and patterning, reactive ion dry etching is used to form the suspension bridge; step S3 is specifically as follows: spin-coating photoresist on the substrate and after photolithography development and patterning, KOH or TMAH is used to wet-etch silicon deep grooves, and the flow gas integrated sensor is obtained after degumming.

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