Gas sensor
By setting slits on the periphery of the insulating film of the gas sensor, the problem of difficulty in heat dissipating between the heater and the insulating film is solved, and efficient rapid heating and power consumption are achieved.
Patent Information
- Application Number
- CN202380041127.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-06-17
- Filing Date
- 2023-05-02
- Publication Date
- 2024-12-27
AI Technical Summary
The existing gas sensors are difficult to dissipate heat due to the closed structure between the heater and the insulating film, resulting in increased power consumption.
In the gas sensor, at least one slit is provided on the outer periphery of the insulating film to reduce heat dissipation, and the contact area between the sensor part and the film is increased by the design of the slit, thereby achieving efficient rapid heating.
Through the design of the slit, the heat dissipation on the insulating film is reduced, the efficiency and sensitivity of the sensor are improved, and the power consumption is reduced.
Smart Images
Figure CN119213301A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a gas sensor. Background Art
[0002] A gas sensor that detects gas based on changes in electrical properties of a sensing film that reacts with gas has been disclosed in the past (for example, see Patent Document 1). In Patent Document 1, a support film for a heater that heats the sensing film to a specific temperature is formed of glass with little heat loss, thereby preventing heat dissipation to the support film side. Prior art literature
[0003] Patent Document 1: Japanese Patent No. 2582343
[0004] In Patent Document 1, the heat of the heater is difficult to dissipate through the support film, but the heat is transferred between the heater and the insulating film on which the temperature sensor is arranged. Therefore, in the closed film structure of Patent Document 1, the heat of the sensing film heated by the heater is transferred to the insulating film for dissipation, which increases the power consumption. Summary of the invention
[0005] An object of the present disclosure herein is to reduce the amount of heat dissipated on the insulating film.
[0006] The gas sensor disclosed herein includes: a substrate; an opening portion arranged on the substrate; an insulating film covering the opening portion; a sensor portion for detecting gas, the sensor portion being mounted on the opening portion of the insulating film; a heater for heating the sensor portion, the heater being mounted on the opening portion of the insulating film; and at least one slit of the insulating film arranged on the periphery of the sensor portion and the heater.
[0007] In the gas sensor of the present disclosure, a terminal end of the slit may be arranged closer to the sensor portion than a position where the insulating film is fixed to the substrate. For example, the insulating film is a closed film formed continuously with the insulating film arranged on the opening. For example, the insulating film is a suspended film anchored to the insulating film fixed to the substrate at three or more locations.
[0008] The opening may be a through hole penetrating the substrate, or a recess provided on the insulating film side while leaving the bottom of the substrate.
[0009] The sensor unit includes: a gas sensing film; and an electrode for measuring an electrical property of the sensing film, wherein the electrode is disposed under the sensing film. In the present disclosure, the heater is disposed under the electrode with at least one insulating film interposed therebetween, a temperature sensor for measuring temperature is provided in the same layer as the heater, and an insulating film is provided under the heater and the temperature sensor.
[0010] One or more sensor portions may be provided on the insulating film, and each of the sensor portions may include the slit.
[0011] The slits may extend from the sensor portion at an equal distance. In addition, the sensor portion may be circular. In this case, the slits may have a curved shape along the outer circumference of the sensor portion.
[0012] The gas sensor of the present disclosure may further include a second substrate that is overlapped on the sensor side of the substrate and has an opening formed therethrough so as to surround the sensor portion.
[0013] Furthermore, the above disclosures can be combined as much as possible.
[0014] According to the gas sensor disclosed in the present invention, since the slit for cutting off the heat transfer on the insulating film is provided, the amount of heat dissipated on the insulating film can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 A configuration example of the gas sensor of the present disclosure is shown. Figure 2 An example of the structure of the AA' cross section is shown. Figure 3 This is an example of the cross-sectional structure of the gas sensor of the present disclosure, (a) shows the BB' cross section, and (b) shows the CC' cross section. Figure 4 These are examples of stress applied to a thin film. (a) shows a case where the slit is short, and (b) shows a case where the slit is long. Figure 5 A configuration example of a sensor unit is shown. Figure 6 This figure shows an example of the change of the slit. Figure 7 A configuration example of the gas sensor of the present disclosure is shown. Figure 8 An example of a manufacturing process of the gas sensor of the present disclosure is shown. Fig. 9 A configuration example of the gas sensor of the present disclosure is shown. Fig.10 An example of the structure of the DD' cross section is shown. Fig.11 A structural example of a DD' cross section is shown. Fig.12A structural example of a multi-layer substrate is shown. DETAILED DESCRIPTION
[0016] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In addition, the present disclosure is not limited to the embodiments shown below. These embodiments are merely illustrative, and the present disclosure can be implemented in various ways of change and improvement based on the knowledge of those skilled in the art. In addition, structural elements with the same reference numerals in the present specification and the accompanying drawings represent structures that are identical to each other.
[0017] (First Embodiment) Figure 1 and Figure 2 A configuration example of the gas sensor of the present disclosure is shown. Figure 1 A top view of a gas sensor is shown. Figure 2 The AA' cross-sectional structure is shown. In the figure, an example is shown in which the thin film 3 is a closed thin film formed continuously with the insulating film arranged on the opening 6. The gas sensor of this embodiment includes: a substrate 1; an opening 6 provided on the substrate 1; a thin film 3 composed of an insulating film covering the opening 6; a sensor part 4 for detecting gas; and at least one slit 5.
[0018] The opening 6 is a gap provided on the surface of the substrate 1 where the thin film 3 is disposed, and may penetrate the substrate 1 or leave the bottom of the substrate 1. The figure shows an example of a structure that penetrates the substrate 1. The sensor unit 4 is mounted on the thin film 3 on the opening 6.
[0019] The slit 5 is an elongated through hole penetrating in the thickness direction of the film 3. At least one slit 5 disposed on the periphery of the sensor portion 4 is disposed on the film 3 on the periphery of the sensor portion 4. In the present embodiment, the slits 5 extending in the Y-axis direction are disposed on both sides of the periphery of the sensor portion 4 in the X-axis direction. The shape of the end of the slit 5 may be curved like a circle or may be rectangular.
[0020] Figure 3 (a) shows an example of a cross-sectional structure of a line BB′ passing through the sensor unit 4 on the Y axis. Figure 3 (b) shows an example of the CC' cross-sectional structure through the slit 5. The end of the slit 5 is as shown in FIG. Figure 3 As shown in (b), the film 3 is arranged closer to the center of the substrate 1 than when it is fixed on the substrate 1. The width of the opening 6 is an arbitrary value larger than the sensor portion 4. In this embodiment, the width in the Y-axis direction is exemplified as D B The length D of the slit 5 in the Y-axis direction is M A length D longer than the width of the sensor portion 4 and wider than the width D B A short arbitrary value.
[0021] Figure 4A comparative example of the length of the slit 5 is shown. The end of the slit 5 shown in the figure is rectangular. It can be seen that the short slit 5S has less influence on the stress of the portion where the sensor unit 4 is arranged than the long slit 5L. In addition, the short slit 5S has less stress on the end of the slit 5 than the long slit 5L, and the range is also narrow. It can be seen that by adjusting the length of the slit 5, the strength of the mounting portion of the sensor unit 4 in the film 3 can be improved, and the sensor unit 4 can be stably fixed.
[0022] Figure 5 4 shows a structural example of the sensor unit 4. The sensor unit 4 can adopt any structure that can detect gas. For example, the sensor unit 4 includes a sensing film 4f, an electrode 4e, a heater 4d, and a temperature sensor 4c. In this embodiment, the film 3 is illustrated as having a lower film 3a and an upper film 3b, and the sensing film 4f and the electrode 4e are arranged on the upper film 3b.
[0023] The sensing film 4f includes a gas sensing material such as a metal oxide film. The electrode 4e is arranged below the sensing film 4f to measure the electrical characteristics of the sensing film 4f. The heater 4d is arranged below the electrode 4e in a manner of sandwiching at least one insulating film therebetween. In the example of this embodiment, the at least one insulating film is the upper film 3b. The heater 4d heats the sensing film 4f. The temperature sensor 4c is arranged near the heater 4d to measure the temperature.
[0024] In order to improve the sensitivity, the sensing film 4f is rapidly heated in the gas sensor. In this embodiment, the contact area between the sensor part 4 and the film 3 is reduced due to the slit 5, so the temperature of the sensor part 4 is difficult to diffuse through the film 3. Therefore, the gas sensor of this embodiment can be efficiently rapidly heated.
[0025] Figure 6 FIG. 4 shows an example of a variation of the slit 5. The shape of the sensor portion 4 is arbitrary. Figure 1 The middle is a rectangle, Figure 6 The example is a circle. There are at least one slit 5 disposed on the outer periphery of the sensor portion 4. The slit 5 may be a straight line, a curve, or may include a partial curve. Figure 6 (a) and Figure 6 As shown in (b), the slit 5 may have a curved shape along the outer periphery of the sensor portion 4. In addition, the length of the slit 5 is arbitrary, such as Figure 1 , Figure 6 (b) Figure 6 (c) and Figure 6 As shown in (d), they may extend from the sensor portion 4 at an equal distance.
[0026] The film 3 illustrated in the present embodiment is a closed film, but the present disclosure is not limited thereto, and any method may be adopted in which the end of the slit 5 is arranged closer to the sensor portion 4 than the position where the film 3 is fixed on the substrate 1. Figure 7 As shown, the suspended film may be anchored to the film 3 fixed on the substrate 1 at three or more locations.
[0027] As described above, according to the present embodiment, since the slit 5 does not extend to the substrate 1, the concentration of internal stress caused by external force, temperature rise or temperature drop can be alleviated. In addition, if the film 3 is a closed film or a suspended film, it is difficult for the gas to bypass the back of the film 3, and the gas introduced from the upper part of the substrate 1 can be efficiently supplied to the sensing film 4f. Furthermore, according to the present disclosure, it is difficult for the low-temperature gas introduced from the substrate 1 to bypass the back of the film 3, so the temperature drop of the sensing film 4f can be suppressed.
[0028] (Second Embodiment) In this embodiment, refer to Figure 8 The manufacturing method of the gas sensor disclosed in the present invention is described. The substrate 1 is, for example, a silicon substrate, and a SiO2 film with a thickness of 5000 Å is formed on the entire surface of the silicon substrate by thermal oxidation. It can also be a plasma oxide film with a thickness in the range of 0.1 μm to 2 μm ( Figure 8 (a)).
[0029] Next, at least one CVD film 2 ( Figure 8 (a) The CVD film 2 may be an oxide film, a reduced pressure nitride film, or a SiON film. The thickness of the CVD film 2 is, for example, in the range of 0.1 μm to 2 μm.
[0030] Next, the film 3, the heater 4d, the temperature sensor 4c and the electrode 4e are formed. Figure 8 (a)). Here, the film 3 is as Figure 5 As shown, a lower film 3a and an upper film 3b are provided, and a heater 4d and a temperature sensor 4c are formed between the lower film 3a and the upper film 3b.
[0031] In addition, the heater 4d and the temperature sensor 4c are formed on the lower film 3a, for example, by forming Pt by sputtering, patterning the heater 4d or the temperature sensor 4c by photolithography, and removing it by dry etching. First, after patterning by photolithography, Pt is formed by sputtering, and patterning can be performed by peeling, or evaporation can be used. The material of the heater 4d or the temperature sensor 4c is not only Pt, but also W and polysilicon. As the bonding layer of the upper film 3b and the lower film 3a, Ti and TiN can be formed, Cr can be formed, and Si can be formed. The thickness of the heater 4d and the temperature sensor 4c is, for example, formed in the range of 0.1μm to 2μm.
[0032] The electrode 4e is formed on the upper film 3b in the same manner as the heater 4d and the temperature sensor 4c. The electrode 4e is formed to have a thickness in the range of 0.1 μm to 1 μm, for example.
[0033] After forming the electrode 4e, next, a slit 5 is formed on the film 3 ( Figure 8 (b)). The heater 4d and the temperature sensor 4c are omitted in this figure. The outer periphery of the area where the sensing film 4f is arranged is patterned in accordance with the shape of the slit 5 by photolithography, and the thin film 3 is removed by dry etching. The thin film 3 can be removed by wet etching or by ion milling.
[0034] Next, an opening 6 ( Figure 8 (c)). Specifically, the back side of the substrate 1 is polished to thin the substrate 1 to a desired thickness, and the back side of the substrate 1 is patterned by photolithography, and dry etching is performed. In this way, an opening 6 penetrating the substrate 1 is formed, and a slit 5 is formed. Alternatively, the substrate 1 may be removed by wet etching, or the surface of the substrate 1 may be patterned to remove the substrate 1 from the surface.
[0035] Next, a sensing film 4f ( Figure 8 (d)). Specifically, the sensing film 4f is coated on the electrode 4e and sintered by annealing. The coating of the sensing film 4f can be performed, for example, by an inkjet method or a dispensing method. In addition, the sensing film 4f can also be formed by a sputtering method. The thickness of the sensing film 4f is the most suitable thickness for detecting the desired gas. The material of the sensing film 4f can be a metal oxide film, a SnO2 film, or a WO3 film.
[0036] By performing the above-described steps, the gas sensor according to the first embodiment can be manufactured.
[0037] (Third Embodiment) Fig. 9The gas sensor of this embodiment has two sensor parts 4A and 4B arranged on the film 3. Figure 8 In the case of the opening 6 shown in (c), the substrate 1 below the thin film 3C between the sensor portions 4A and 4B may be removed or may be left.
[0038] Fig.10 and Fig.11 This is an example of a structure showing the D-D' section. Fig.10 As shown, the film 3C may have an opening 6 below. Fig.11 As shown, there may also be a substrate 1 under the film 3C.
[0039] In this embodiment, even when two or more sensor units 4 are arranged on the film 3, the film 3C is arranged between the sensor units 4A and 4B. Therefore, the present disclosure can efficiently introduce gas into the surface of the film 3.
[0040] Moreover, according to the gas sensor disclosed herein, when two or more sensor parts 4A and 4B are arranged on the film 3, since there is a film 3C between the sensor parts 4, it is difficult for gas to flow into the back side of the film 3 under the sensor parts 4A and 4B, which can suppress the cooling caused by the introduced gas.
[0041] (Fourth Embodiment) Fig.12 The cross-sectional structure example of the gas sensor of this embodiment is shown. The gas sensor of this embodiment has a multilayer structure in which a plurality of substrates are overlapped. As an example, Fig.12 The following example indicates: Figure 2 In the gas sensor shown, the substrate 101 is stacked on the sensor portion 4 side of the substrate 1 and connected via the electrode 7 and the through electrode 107 .
[0042] The substrate 101 is formed with an opening 106 that penetrates so as to surround the sensor unit 4. In this way, the gas can react efficiently with the sensor unit 4 in the opening 106. The shape of the opening 106 in the XY plane is arbitrary, and can be the same as or different from the opening 6. The shape of the opening 106 in the XY plane can be a shape that can generate a certain flow of gas toward the sensor unit 4.
[0043] In addition, in this embodiment, wiring is formed on the substrate 101, an opening 106 is formed, and a through electrode 107 is formed, which can be connected with Figure 2 The gas sensor shown is made by bonding. The bonding may be metal bonding or room temperature bonding. In addition, in order to transmit the potential between the upper and lower substrates 1, a plurality of substrates may be connected by electrodes 7.
[0044] In addition, if Fig.12 As shown, the opening 6 of the present disclosure may be a depression which is provided on the side of the film 3 and retains the bottom of the substrate 1 . Description of Reference Numerals
[0045] 1: Substrate 2: CVD film 3: Film 3a: Lower film 3b: Upper film 4, 4A, 4B: Sensor part 4c: Temperature sensor 4d: Heater 4e, 7: Electrode 4f: Perception membrane 5: Slit 6, 106: Opening 107: Through the electrode
Claims
1. A gas sensor, characterized in that include: substrate; An opening portion disposed on the substrate; an insulating film covering the opening; a sensor portion for detecting gas, the sensor portion being mounted on the insulating film on the opening; a heater for heating the sensor portion, the heater being mounted on the insulating film on the opening; and At least one slit of the insulating film is disposed at the periphery of the sensor portion and the heater.
2. The gas sensor according to claim 1, characterized in that The end of the slit is arranged closer to the sensor portion than a position where the insulating film is fixed to the substrate.
3. The gas sensor according to claim 1, characterized in that: The insulating film is a closed film formed continuously with the insulating film disposed on the opening.
4. The gas sensor according to claim 1, characterized in that: The insulating film is a suspended film anchored to the insulating film fixed to the substrate at three or more locations.
5. The gas sensor according to claim 1, characterized in that: A second substrate is further provided, the second substrate being overlapped on the sensor portion side of the substrate and having an opening formed therethrough so as to surround the sensor portion.
6. The gas sensor according to claim 1, characterized in that The opening is a through hole penetrating the substrate. Alternatively, the bottom of the substrate is retained and a recess is provided on the insulating film side.
7. The gas sensor according to claim 1, characterized in that: The sensor unit includes: a sensing membrane for sensing the gas; and an electrode for measuring the electrical properties of the sensing film, the electrode being arranged under the sensing film, The heater is arranged under the electrode in a manner of sandwiching at least one insulating film therebetween. A temperature sensor for measuring temperature is provided on the same layer as the heater, An insulating film is provided under the heater and the temperature sensor.
8. The gas sensor according to claim 1, characterized in that One or more sensor portions are provided on the insulating film, The sensor parts each include the slit.
9. The gas sensor according to claim 1, characterized in that: The slits extend from the sensor portion at equal distances.
10. The gas sensor according to claim 1, characterized in that The sensor portion is circular, The slit has a curved shape along an outer circumference of the sensor portion.