Capacitive hydrogen sensor and preparation method thereof

Abstract

The present application relates to the field of semiconductor technology, and specifically to a capacitive hydrogen sensor and a method for manufacturing the same, comprising: an electrode layer formed on a dielectric layer of the substrate, a first electrode and a second electrode being arranged in an interdigitated manner; a hydrogen sensitive layer formed on the electrode layer, and the hydrogen sensitive layer being a polymer film with a mesh structure. The present invention uses a polymer film with a mesh structure as a hydrogen sensitive layer, so that the hydrogen sensitive layer can have a sufficiently high hydrogen permeability, so that the capacitive hydrogen sensor has a higher sensitivity and a faster response speed. In addition, the first electrode and the second electrode are arranged in an interdigitated manner, so that the effective area of ​​the entire capacitive hydrogen sensor becomes larger, the capacitance is large, and the sensitivity is high. It is worth mentioning that the manufacturing process in this embodiment is perfectly compatible with the CMOS process platform, greatly reducing the size of the device and making it easy to combine with an integrated circuit chip.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a capacitive hydrogen sensor and a method for preparing the same. Background Art

[0002] In the field of new energy, hydrogen fuel is widely used in aerospace, aviation and automobile fields due to its advantages of no pollution, no noise and high efficiency. This requires the detection or detection of changes in environmental hydrogen concentration to respond to faults or abnormal conditions in a timely manner. At present, hydrogen fuel cell vehicles generally detect changes in environmental hydrogen concentration by adding hydrogen sensors or hydrogen leakage detection devices.

[0003] Traditional hydrogen sensors are resistive. The electrons in hydrogen combine with the oxygen ions in its chemical adsorption layer to detect the ambient hydrogen concentration through changes in carrier concentration. However, traditional hydrogen sensors are difficult to combine with IC chips due to their large size, high power consumption, and slow response speed, and their application scenarios are greatly limited. Summary of the invention

[0004] The present application solves the above technical problems in the related art at least to a certain extent. To this end, the present application proposes a capacitive hydrogen sensor and a preparation method thereof to solve at least one of the above technical problems.

[0005] In order to achieve the above-mentioned object, the first aspect of the present application provides a capacitive hydrogen sensor, comprising:

[0006] substrate;

[0007] The electrode layer is formed on the dielectric layer of the substrate, and the electrode layer includes a first electrode and a second electrode.

[0008] The first electrode and the second electrode are arranged in an interdigitated manner;

[0009] The hydrogen sensitive layer is formed on the electrode layer, and the hydrogen sensitive layer is a polymer with a mesh structure.

[0010] Physical film.

[0011] A second aspect of the present application provides a method for manufacturing a capacitive hydrogen sensor, comprising the following steps:

[0012] Providing a substrate, and sequentially depositing an insulating layer and a stop layer on the substrate;

[0013] Define the area and shape of the stop layer;

[0014] Depositing a dielectric layer on the stop layer, planarizing the dielectric layer, and defining a plurality of through holes in the dielectric layer;

[0015] Depositing an electrode layer on the dielectric layer to define a first electrode, a second electrode, and a third electrode of the electrode layer;

[0016] Depositing a passivation layer on the electrode layer, completely removing the passivation layers in the first electrode and second electrode regions, and retaining the passivation layers in the third electrode region and other connection circuits to form a sensitive capacitance detection electrode region;

[0017] forming a bonding pad area;

[0018] The hydrogen sensitive layer is coated, the hydrogen sensitive layer on the pressure welding block is removed, the hydrogen sensitive layer in the first electrode, the second electrode and the third electrode regions is retained, and finally a curing treatment is performed to complete the production of the capacitive hydrogen sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Also, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0020] Figure 1 A schematic cross-sectional view of the structure of a MEMS hydrogen sensor in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0021] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0022] Various structural schematic diagrams according to embodiments of the present disclosure are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may further design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0023] In the context of the present disclosure, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element or an intervening layer / element may exist between them. In addition, if a layer / element is "on" another layer / element in one orientation, the layer / element may be "below" the other layer / element when the orientation is reversed.

[0024] like Figure 1As shown, this embodiment provides a micro-electromechanical (MEMS) capacitive hydrogen sensor 100, comprising a substrate 10, an insulating layer 11, a stop layer 12, a dielectric layer 13, an electrode layer 14, a bonding layer 15, a passivation layer 16 and a hydrogen sensitive layer 17, wherein the insulating layer 11, the stop layer 12, and the dielectric layer 13 are sequentially formed on the substrate 10 from bottom to top, a portion of the dielectric layer 13 is directly in contact with the insulating layer 11, and the electrode layer 14 is formed on the dielectric layer 13, and the electrode layer 14 includes a first electrode 140, a second electrode 141 and a third electrode 14 3. The first electrode 140 and the second electrode 141 serve as the positive and negative electrodes of the capacitive hydrogen sensor 100, respectively. The third electrode 143 serves as the ground terminal of the capacitive hydrogen sensor 100. The first electrode 140 and the second electrode 141 are arranged in an interdigitated manner. The third electrode 143 is located at the periphery of the first electrode 140 and the second electrode 141. Specifically, the third electrode 143 fully surrounds or semi-surrounds the first electrode 140 and the second electrode 141, and the third electrode 143 passes through a plurality of through holes 130 on the dielectric layer 13 to form an interconnection with the stop layer 12.

[0025] Furthermore, a bonding layer 15 is formed on the dielectric layer 13 for connecting external wires, and a passivation layer 16 is formed in the third electrode 143 region of the electrode layer 14 and on the bonding layer 15 .

[0026] In some embodiments of the present invention, the stop layer 12 is in a comb-tooth shape and is staggered with the first electrode 140 and the second electrode 141 ; or the stop layer 12 is in a square shape and is placed below the electrode layer 14 .

[0027] It is worth mentioning that the hydrogen sensitive layer 17 is formed on the electrode layer 14. Specifically, there is a gap between the first electrode 140 and the second electrode 141. A portion of the hydrogen sensitive layer 17 is formed on the upper surfaces of the first electrode 140, the second electrode 141 and the passivation layer 16. Another portion of the hydrogen sensor 17 fills the gap between the first electrode 140 and the second electrode 141, and extends downward to contact the stop layer 12. It can be understood that the hydrogen sensitive layer 17 serves as a dielectric layer of the capacitive hydrogen sensor 100.

[0028] It should be noted that the hydrogen sensitive layer 17 is a polymer film with a mesh structure, so that the hydrogen sensitive layer 17 can have a sufficiently high hydrogen permeability, so that the capacitive hydrogen sensor 100 has a higher sensitivity and a faster response speed. Specifically, the polymer film can be selected from a combination of one or more of microporous polymers, facilitated transport polymeric membranes, Langmuir-Blodgett films (LB), layer-by-layer deposited polyelectrolyte multilayers (PEMs), polyamides, and metal-organic framework thin films (MOF).

[0029] In some embodiments of the present invention, the material of the stop layer 12 is the same as or different from that of the dielectric layer 13. The material of the stop layer 12 can be aluminum, aluminum silicon, aluminum copper and other commonly used metal materials for semiconductors, and the dielectric layer 13 can be silicon dioxide, silicon nitride or a composite thereof; the substrate 10 is a silicon substrate of CMOS front-end and part of back-end processes with processed circuits. Alternatively, the substrate 10 is a silicon wafer, glass, or ceramic substrate, and an insulating layer is deposited to be used as a MEMS discrete device. The material of the electrode layer 14 is one or more of the following materials: aluminum, aluminum silicon, aluminum copper, and the passivation layer 16 can be silicon dioxide, silicon nitride or a composite thereof.

[0030] In an embodiment of the present invention, the substrate 10 is a silicon wafer, the insulating layer 11 is an oxide layer, the stop layer 12 is an aluminum layer, the dielectric layer 13 is an oxide layer, the electrode layer 14 is an aluminum layer, and is defined as a sensitive capacitance detection electrode area, a shielding area, and a bonding layer area. The passivation layer 16 may be a composite layer of silicon dioxide and silicon nitride. The hydrogen sensitive layer 17 may be a microporous polymer film.

[0031] The manufacturing process of the MEMS capacitive hydrogen sensor 100 described in this embodiment is as follows:

[0032] S1: Prepare a silicon wafer substrate 10, and deposit an insulating layer 11 on the wafer; the insulating layer 11 is made by growing silicon oxide through thermal oxidation, or depositing silicon oxide or silicon nitride through CVD process, or a composite layer thereof.

[0033] S2: depositing a layer of aluminum as a stop layer 12 on the insulating layer 11 by magnetron sputtering or evaporation process, and further defining the region and comb shape of the stop layer 12 by photolithography and etching process;

[0034] S3: depositing a dielectric layer 13 by a CVD process, planarizing the dielectric layer 13 by a CMP process, and defining a plurality of through holes 130 by photolithography and etching processes;

[0035] S4: depositing a layer of aluminum as an electrode layer 14 on the dielectric layer 13 by magnetron sputtering or evaporation process, further defining a first electrode 140, a second electrode 141, a third electrode 143 and a bonding layer 15 by photolithography and etching process; the thickness of the electrode layer 14 is 0.1-5 μm. The interdigital width of the first electrode 140 and the second electrode 141 is 0.01-2 μm. The side spacing of the first electrode 140 and the second electrode 141 is 0.01-2 μm.

[0036] S5: Deposit a passivation layer 16 on the electrode layer 14 through a PECVD process, and further, completely remove the passivation layer 16 in the first electrode and second electrode regions through a photolithography and etching process, retain the passivation layer 16 in the third electrode region and other connection circuits, and form a sensitive capacitance detection electrode region; the thickness of the passivation layer 16 is 0.5-5 μm. Preferably, the passivation layer 16 in the first electrode and second electrode regions is etched by dry etching technology, and the surface and sidewall of the first electrode 140 and the second electrode 141, as well as the passivation layer 16 between the first electrode 140 and the second electrode 141 are etched cleanly, and after the first electrode 140 and the second electrode 141 are completely exposed, continue to over-etch the dielectric layer 13 between the first electrode 140 and the second electrode 141 until the stop layer 12 is etched to form an etched groove penetrating the passivation layer 16, the electrode layer 14 and the dielectric layer 13, wherein the height difference between the lower surface of the electrode layer 14 and the bottom of the etched groove is 0.05-1um.

[0037] S6: forming a pad region by photolithography of a pad plate, and etching the passivation layer 16 to open the pad layer 15. Obviously, the pad layer 15 can also be opened at the same time in step S5, and step S6 can be omitted, that is, the sensitive capacitor detection electrode region and the pad region are formed at the same time, or the pad region is formed after the sensitive capacitor detection electrode region is formed.

[0038] S7: coating a microporous polymer film as the hydrogen sensitive layer 17, removing the hydrogen sensitive layer 17 on the bonding layer 15 through processes such as photolithography and development, and finally curing to complete the manufacture of the MEMS capacitive hydrogen sensor 100. The thickness of the cured hydrogen sensitive layer 17 is 1-10 μm.

[0039] Compared with the prior art, this embodiment uses a polymer film with a mesh structure as a hydrogen sensitive layer, so that the hydrogen sensitive layer can have a sufficiently high hydrogen permeability, so that the capacitive hydrogen sensor has a higher sensitivity and a faster response speed. In addition, the first electrode and the second electrode are arranged in a staggered manner in a forked finger shape, so that the effective area of ​​the entire capacitive hydrogen sensor becomes larger, the capacitance is large, and the sensitivity is high. It is worth mentioning that the manufacturing process in this embodiment is perfectly compatible with the CMOS process, greatly reducing the size of the device and making it easy to combine with an integrated circuit chip.

[0040] In the above description, the technical details of the patterning and etching of each layer are not described in detail. However, those skilled in the art should understand that various technical means can be used to form layers, regions, etc. of desired shapes. In addition, in order to form the same structure, those skilled in the art can also design methods that are not completely the same as the methods described above. In addition, although the various embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage.

[0041] The embodiments of the present disclosure are described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure. The scope of the present disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, a person skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A capacitive hydrogen sensor, It is characterized in that include: substrate; The electrode layer is formed on the dielectric layer of the substrate, and the electrode layer includes a first electrode and a second electrode. The first electrode and the second electrode are arranged in an interdigitated manner; The hydrogen sensitive layer is formed on the electrode layer, and the hydrogen sensitive layer is a polymer with a mesh structure. The polymer membrane is selected from a combination of one or more of a microporous polymer membrane, a facilitated transfer polymer membrane, a Langmuir-Blodgett membrane, a layer-by-layer self-assembled polyelectrolyte multilayer membrane, a polyamide membrane, and a metal-organic skeleton membrane.

2. The capacitive hydrogen sensor according to claim 1, It is characterized in that The substrate is a silicon substrate of CMOS front-end and part of back-end processes with processed circuits; or the substrate is a silicon wafer, glass or ceramic substrate, and an insulating layer is deposited to be used as a MEMS discrete device.

3. The capacitive hydrogen sensor according to claim 1, It is characterized in that The electrode layer further includes a third electrode, which fully surrounds or half surrounds the first electrode and the second electrode.

4. The capacitive hydrogen sensor according to claim 3, It is characterized in that Also includes: An insulating layer and a stop layer are sequentially formed on the substrate, wherein the dielectric layer is formed on the stop layer, and a portion of the dielectric layer is directly in contact with the insulating layer, and the third electrode is interconnected with the stop layer via a plurality of through holes; A bonding layer, formed on the dielectric layer, for connecting external wires; A passivation layer is formed on the third electrode region of the electrode layer and the bonding layer.

5. The capacitive hydrogen sensor according to claim 4, It is characterized in that The stop layer is in a comb-tooth shape and is staggered with the first electrode and the second electrode; or The stop layer is in a square shape and is placed below the electrode layer.

6. The capacitive hydrogen sensor according to claim 4, It is characterized in that The dielectric layer is silicon dioxide, silicon nitride or a composite of the two; the material of the electrode layer is selected from: one or more of aluminum, aluminum silicon and aluminum copper; the passivation layer is silicon dioxide, silicon nitride or a composite of the two.

7. The capacitive hydrogen sensor according to claim 1, It is characterized in that The interdigital width and the side distance between the first electrode and the second electrode are 0.01-2 μm.

8. A method for manufacturing the capacitive hydrogen sensor according to any one of claims 1 to 7, It is characterized in that The following steps are involved: Providing a substrate, and sequentially depositing an insulating layer and a stop layer on the substrate; Define the area and shape of the stop layer; Depositing a dielectric layer on the stop layer, planarizing the dielectric layer, and defining a plurality of through holes in the dielectric layer; Depositing an electrode layer on the dielectric layer to define a first electrode, a second electrode and a third electrode of the electrode layer; Depositing a passivation layer on the electrode layer, completely removing the passivation layers in the first electrode and second electrode regions, and retaining the passivation layers in the third electrode region and other connection circuits to form a sensitive capacitance detection electrode region; forming a bonding pad area; The hydrogen sensitive layer is coated, the hydrogen sensitive layer on the pressure welding block is removed, the hydrogen sensitive layer in the first electrode, the second electrode and the third electrode regions is retained, and finally a curing treatment is performed to complete the production of the capacitive hydrogen sensor.

9. The method for manufacturing a capacitive hydrogen sensor according to claim 8, It is characterized in that The removing of the passivation layer in the first electrode and the second electrode region comprises: removing the surface and the sidewall of the first electrode and the second electrode, and the passivation layer between the first electrode and the second electrode, and continuing to over-etch the dielectric layer between the first electrode and the second electrode after the first electrode and the second electrode are completely exposed, until the stop layer is etched to form an etching groove penetrating the passivation layer, the electrode layer and the dielectric layer; The sensitive capacitance detection electrode region and the pad region are formed simultaneously, or the pad region is formed after the sensitive capacitance detection electrode region is formed.

10. The method for manufacturing a capacitive hydrogen sensor according to claim 9, It is characterized in that The material of the stop layer is the same as or different from that of the dielectric layer, and the height difference between the lower surface of the electrode layer and the bottom of the etched groove is 0.05-1 μm.

11. The method for manufacturing a capacitive hydrogen sensor according to claim 8, It is characterized in that The manufacturing method of the capacitive hydrogen sensor is compatible with CMOS technology.

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