Sensor element and gas sensor

Abstract

To provide a sensor element and gas sensor, capable of cancelling thermal stress due to heating, avoiding deformation in a membrane structure and obtaining the stability of the gas sensor.SOLUTION: A sensor element includes a substrate including a cavity part and an opening communicating with the cavity part and a membrane provided in the substrate, supported on the opening and partially covering the cavity part and including first and second heating resistance members. Each of the first and second heating resistance members is formed in a fold line shape; the first heating resistance member is provided on the side close to the cavity part of the membrane; the second heating resistance member is provided on the side distant from the cavity part of the membrane; and the straight-line part of the end part of the first heating resistance member and the straight-line part of the end part of the second heating resistance member are constituted to at least partially overlap so as to cancel a thermal stress due to the first heating resistance member and a thermal stress due to the second heating resistance member to each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the technical field of gas sensors, and more particularly to a sensor element and a gas sensor. [Background technology]

[0002] A gas sensor is a device capable of detecting specific gases and their concentrations in the environment, converting information about the type and concentration of the gas into an electrical signal, enabling detection, monitoring, analysis, and warning. The gas sensor is equipped with a heating device and a membrane structure. The heating device improves the gas sensor's responsiveness to gases and increases detection sensitivity, while the membrane structure reduces heat transfer to the outside, allowing efficient heating only within the membrane and reducing the energy required for heating. Conventional gas sensors are disclosed, for example, in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2024-86564 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when used for a long period of time, heat generated inside the gas sensor generates thermal stress, which distorts the membrane structure. This distortion changes the resistance characteristics inside the gas sensor and affects the detection sensitivity. Therefore, ensuring stable use of gas sensors and avoiding deformation of the membrane structure is a technical challenge that must be solved as soon as possible by those skilled in the art.

[0005] Therefore, the present invention has been made to solve the above problems, and aims to provide a sensor element and a gas sensor that have a double-layer structure that combines a first heating resistance member and a second heating resistance member, which can cancel out thermal stresses caused by heating, avoid deformation of the membrane structure, and ensure the stability of the gas sensor. [Means for solving the problem]

[0006] In order to solve the above technical problems, an embodiment of the present invention provides a sensor element comprising a substrate and a membrane provided on the substrate, wherein the substrate has a cavity and an opening communicating with the cavity, the membrane is supported on the opening and partially covers the cavity, the membrane includes a first heating resistance element and a second heating resistance element, the first heating resistance element and the second heating resistance element are both shaped in a folded linear shape, the first heating resistance element is provided on a side of the membrane closer to the cavity, and the second heating resistance element is provided on a side of the membrane farther from the cavity, and the straight portion of the end of the first heating resistance element and the straight portion of the end of the second heating resistance element are configured to at least partially overlap so that thermal stresses due to the first heating resistance element and the second heating resistance element cancel each other out.

[0007] In one preferred embodiment, the membrane further comprises a thermistor electrode and a thermistor material, the thermistor electrode being located flush with the first heating resistive element or the second heating resistive element, and the thermistor material at least partially covering the thermistor electrode.

[0008] In one preferred embodiment, the membrane further comprises a thermistor electrode and a thermistor material, wherein the first heating resistance element is located on a side of the membrane closer to the cavity, the second heating resistance element is located on a side of the membrane farther from the first heating resistance element, the thermistor electrode is located on a side of the membrane farther from the second heating resistance element, and the thermistor material at least partially covers the thermistor electrode.

[0009] In one preferred embodiment, the membrane further comprises a first thermistor electrode, a first thermistor material, and a second thermistor electrode, wherein the first thermistor electrode is located flush with the first heating resistive element, the first thermistor material at least partially covering the first thermistor electrode, and the second thermistor electrode is located flush with the second heating resistive element.

[0010] In one preferred embodiment, the membrane further comprises a second thermistor material, the second thermistor material at least partially covering the second thermistor electrode.

[0011] In one preferred embodiment, the thermistor electrode is provided within a non-linear portion of the first heating resistive element or the second heating resistive element.

[0012] In one preferred embodiment, the bending direction of the non-linear portion of the first heating resistive element is rotated 180° relative to the bending direction of the non-linear portion of the second heating resistive element.

[0013] In one preferred embodiment, the first and second heating resistive elements are connected in parallel in a circuit.

[0014] In one preferred embodiment, the circuit further comprises a voltage amplifier that allows adjustment of the voltage applied to the first and second resistive heating elements.

[0015] In one preferred embodiment, the membrane further comprises an insulator disposed between the first heating resistance element and the second heating resistance element, and the first heating resistance element and the second heating resistance element are separated from each other by the insulator.

[0016] In one preferred embodiment, the membrane further comprises a first insulator, the thermistor electrode is located in the same plane as the second heating resistance element, the thermistor material at least partially covers the thermistor electrode and the second heating resistance element, the first insulator is provided below the second heating resistance element, the first insulator partially covers the first heating resistance element, and the first heating resistance element is provided on the side of the first insulator farther from the second heating resistance element.

[0017] In one preferred embodiment, the sensor element further comprises a second insulator, the second insulator being provided under the first heating resistance member.

[0018] In one preferred embodiment, the membrane has a dummy pattern that expands upon exposure to heat to counteract deformation caused by the thermistor electrodes.

[0019] In one preferred embodiment, the sensor element further includes a thermal via, and the first heating resistance member and the second heating resistance member are thermally coupled through the thermal via.

[0020] In one preferred embodiment, during operation of the sensor, a voltage applied to the first heating resistive element is designated as a first voltage, a voltage applied to the second heating resistive element is designated as a second voltage, and the first voltage is equal to or greater than the second voltage.

[0021] And, another embodiment of the present invention provides a gas sensor including the sensor element as described above. [Effects of the Invention]

[0022] As described above, compared with the prior art, the embodiments of the present invention have at least one beneficial effect as described below: By combining the first heating resistor and the second heating resistor, the thermal stress in the thickness direction of the membrane caused by the heat generated by the first heating resistor is in the opposite direction to the thermal stress in the thickness direction of the membrane caused by the heat generated by the second heating resistor, allowing the stresses to cancel each other out, canceling out the thermal stress in the thickness direction of the membrane and significantly reducing the thermal stress in the thickness direction of the membrane, effectively preventing deformation of the membrane structure, and as a result, the resistance characteristics of the gas sensor are stable and less likely to change, ensuring stable performance of the gas sensor. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic diagram showing the structure of a first embodiment of the present invention. [Figure 2] FIG. 2 is a side view of the first embodiment of the present invention in the xz plane. [Figure 3] 3 is a top view of plane A of the first embodiment of the present invention in FIG. 2. FIG. [Figure 4] 3 is a top view of plane B of the first embodiment of the present invention in FIG. 2. FIG. [Figure 5] FIG. 2 is a schematic diagram showing a circuit for driving a first heating resistive element and a second heating resistive element of the present invention. [Figure 6] FIG. 10 is a diagram showing a simulation result when a voltage is applied to a first heating resistance member. [Figure 7] FIG. 10 is a diagram showing a simulation result when a voltage is applied to a second heating resistance member. [Figure 8] FIG. 4 is a diagram showing a simulation result when a voltage is applied to the first heating resistance member and the second heating resistance member according to the first embodiment of the present invention. [Figure 9] FIG. 9 is a diagram comparing the simulation results of the present invention shown in FIGS. 6 to 8. [Figure 10] FIG. 4 is a schematic diagram showing the structure of a second embodiment of the present invention. [Figure 11]FIG. 10 is a side view (in the −y-axis direction) of the second embodiment of the present invention. [Figure 12] 12 is a view of the plane A in FIG. 11 of the present invention as viewed from above (+z-axis direction). [Figure 13] 12 is a view of the plane B in FIG. 11 of the present invention as viewed from above (+z-axis direction). [Figure 14] FIG. 10 is a schematic diagram showing the structure of a third embodiment of the present invention. [Figure 15] FIG. 10 is a side view (in the −y-axis direction) of the third embodiment of the present invention. [Figure 16] 16 is a view of the plane A in FIG. 15 of the present invention as seen from above (+z-axis direction). [Figure 17] 16 is a view of the plane B of FIG. 15 of the present invention as viewed from above (+z-axis direction). [Figure 18] FIG. 10 is a schematic diagram showing two thermistor electrodes of a third embodiment of the present invention. [Figure 19] FIG. 10 is a schematic diagram showing the structure of a fourth embodiment of the present invention. [Figure 20] FIG. 10 is a side view (in the −y-axis direction) of the fourth embodiment of the present invention. [Figure 21] FIG. 10 is a top view of plane A of the fourth embodiment of the present invention. [Figure 22] FIG. 10 is a top view of plane B of the fourth embodiment of the present invention. [Figure 23] FIG. 10 is a schematic diagram showing the structure of a fifth embodiment of the present invention. [Figure 24] FIG. 10 is a plan view of the fifth embodiment of the present invention, corresponding to FIG. 4 of the first embodiment. [Figure 25] FIG. 2 is a schematic diagram showing a circuit for driving a first heating resistive element and a second heating resistive element of the present invention. [Figure 26] 1 is a schematic diagram of a circuit including a voltage amplifier of the present invention; [Figure 27] 1A and 1B are diagrams showing a first shape and structure design of each member of the present invention. [Figure 28] 10A and 10B are diagrams showing a second shape and structure design of each member of the present invention. [Figure 29] 10A and 10B are diagrams showing a third shape structure design of each member of the present invention. [Figure 30] 10A and 10B are diagrams showing a fourth shape structure design of each member of the present invention. [Figure 31] FIG. 10 is a diagram showing a fifth shape structure design of each component of the present invention. [Figure 32] FIG. 10 is a diagram showing a sixth shape structure design of each component of the present invention. [Figure 33] FIG. 2 is a diagram showing a plane on which a dummy pattern of the first structure of the present invention is provided. [Figure 34] FIG. 10 is a diagram showing a plane on which dummy patterns of the second structure of the present invention are provided. [Figure 35] FIG. 10 is a diagram showing a plane on which dummy patterns of the third structure of the present invention are provided. [Figure 36] FIG. 10 is a diagram showing a plane on which dummy patterns of a fourth structure of the present invention are provided. [Figure 37] FIG. 10 is a diagram showing a plane on which dummy patterns of the fifth structure of the present invention are provided. [Figure 38] 1 is a graph relating to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention, but it is obvious that the described embodiments are only a part of the embodiments of the present invention, and are not all of the embodiments, and these embodiments are provided to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments that can be obtained by those skilled in the art without requiring creative efforts fall within the protection scope of the present invention.

[0025] As used herein, terms such as "first," "second," "third," etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or as implicitly specifying the number of technical features shown. Thus, features defined as "first," "second," "third," etc. may be understood to expressly or implicitly denote the inclusion of one or more of the features. As used herein, unless otherwise specified, "one or more" means two or more.

[0026] In this specification, unless otherwise expressly limited, the terms "attached," "connected," and "coupled" should be understood in a broad sense. For example, "connected" may mean a fixed connection, a detachable connection, or an integral connection, a mechanical connection, an electrical connection, a direct connection, an indirect connection via an intermediate medium, or a connection between two elements.

[0027] As used herein, terms such as "vertical," "horizontal," "left," "right," "top," "bottom," and similar expressions are used for descriptive purposes only and do not indicate or imply that the referenced device or element must have a particular orientation, be configured, or operate in a particular manner, and therefore are not intended to limit the present invention. As used herein, the term "and / or" includes any and all combinations of one or more listed associated items. Those skilled in the art will understand the specific meaning of the above terms in this application depending on the specific circumstances.

[0028] Unless otherwise defined in this specification, the meanings of all technical and scientific terms used in the present invention are the same as those commonly understood by those skilled in the art. The terms used in the specification of the present invention are used only for the purpose of describing specific embodiments and are not intended to limit the present invention. Those skilled in the art can understand the specific meanings of the above terms in this application according to specific circumstances.

[0029] First Embodiment Conventional heating components / devices in gas sensors typically use planar pattern coils, such as meander or spiral coils. Planar coils are thin and therefore capable of efficiently heating flat membrane structures. A thicker membrane structure increases its heat capacity, requiring more input energy for heating and resulting in uneven heating within the membrane. Therefore, a thinner membrane structure is desirable. However, a thinner membrane structure can cause thermal stress due to the heat generated by heating, leading to deformation of the membrane structure. Furthermore, prolonged use of the gas sensor can accelerate this deformation process.

[0030] In heated gas sensors, a thermistor is generally placed on the surface of the membrane that comes into contact with the outside air, either above or below it. However, when the membrane deforms, the thermistor structure also deforms, causing problems such as changes in resistance characteristics. Therefore, to stabilize the characteristics of the gas sensor over the long term, it is necessary to prevent the membrane from deforming.

[0031] Specifically, as shown in FIG. 1 showing a schematic structure of the first embodiment of the present invention, the sensor element 101 according to the first embodiment of the present invention comprises a substrate 102 and a membrane 104 provided on the substrate 102, and the membrane 104 includes a first heating resistance member 105 and a second heating resistance member 106.

[0032] The substrate 102 is also called a base material. The base material is preferably one having appropriate mechanical strength and may be made of a material suitable for microfabrication such as etching, and examples of the base material include, but are not limited to, a silicon single crystal substrate, a single crystal sapphire substrate, a ceramic substrate, a quartz substrate, and a glass substrate.

[0033] In an embodiment of the present invention, the substrate 102 has a rectangular parallelepiped structure, a cavity 103 is provided in its center, and an opening communicating with the cavity 103 is formed on the surface of the substrate 102. The membrane 104 is provided toward the upper portion of the substrate 102. The presence of the cavity 103 prevents the center of the membrane 104 from coming into direct contact with the substrate 102. The opening is partially covered by the membrane 104, and as shown in FIG. 1, the membrane 104 is provided at the center of the opening so as to be supported by four diagonal arms above the opening. In other words, although the membrane 104 is provided over the opening, it is not completely covered by the membrane 104, forming a gap 112. As shown in FIG. 1, four approximately trapezoidal gaps are formed. With this configuration, the membrane 104 is supported at multiple points around the opening and fixed to the substrate 102.

[0034] The first heating resistance member 105 and the second heating resistance member 106 are both formed in a bent linear shape, including a linear portion and a non-linear meander portion. For example, the bent linear (meander-shaped) input and output wires of the first heating resistance member 105 in the lower layer are located below the bent linear (meander-shaped) input and output wires of the second heating resistance member 106 in the upper layer, and the linear portions at the beginning and end of the meander portion of the first heating resistance member 105 at least partially overlap with the linear portions at the beginning and end of the meander portion of the second heating resistance member 106. Preferably, the first heating resistance member 105 and the second heating resistance member 106 are isolated by an insulator 110 to prevent electrical contact. Alternatively, the substrate 102 may be made of a conductive material such as a commonly known Si substrate by a MEMS process, in which case the substrate 102 and the first heating resistance member 105 are separated by an insulator 110 to prevent electrical contact.

[0035] In this embodiment, the first heating resistance member 105 is provided below the membrane 104. Meanwhile, the second heating resistance member 106 is provided above the membrane 104. As shown in Fig. 2, which is a side view showing the xz plane of the first embodiment of the present invention, the first heating resistance member 105 is in electrical contact with the pad 113a via a contact surface 111 between the first heating resistance member 105 and the pad, and a bonding wire 109a is connected to the pad 113a with which the first heating resistance member is in contact.

[0036] Similarly, pad-shaped portions are provided at both ends of the second heating resistance member 106, and bonding wires 109b are connected to these pad-shaped portions. Although the ends of the bonding wires 109a and 109b are omitted in the drawing, as shown in Fig. 5, these ends are connected to circuits for supplying power to the first heating resistance member 105 and the second heating resistance member 106.

[0037] As described above, the membrane 104 is in contact with the substrate 102 with the cavity 103 and the gap 112 formed therebetween, thereby reducing the heat capacity of the membrane 104 and the thermal conduction between the membrane 104 and the substrate 102. Because the heat capacity and thermal conduction of the membrane 104 are reduced in this way, the membrane 104 can be heated efficiently and quickly by Joule heat generated by applying voltage to the first heating resistance member 105 and the second heating resistance member 106, and the rate of temperature decrease also increases when the voltage to the first heating resistance member 105 and the second heating resistance member 106 is set to zero, i.e., turned off.

[0038] The above-described sensor element can be used to configure a heating device for a compact gas sensor, but in order to configure the gas sensor, it is also necessary to provide a thermistor electrode 107 and a thermistor material 108 on the membrane 104.

[0039] The thermistor electrode 107 is a pattern made of a conductor such as copper, silver, gold, or platinum, and is provided on the same plane as the first heating resistance member 105 or the second heating resistance member 106. In this embodiment, the thermistor electrode 107 is provided on the same plane as the second heating resistance member 106. As shown in FIGS. 1 and 4 (FIG. 4 is a schematic diagram of the first embodiment of the present invention shown in FIG. 2, viewed from above on side B; in this figure, the first heating resistance member and the bonding wires connected to the first heating resistance member are omitted for ease of understanding the top surface configuration), the thermistor electrode 107 is preferably provided inside a recess in the nonlinear portion (meander portion) of the second heating resistance member 106. Providing the thermistor electrode 107 in this manner improves the efficiency of heat conduction, enabling Joule heat generated in the second heating resistance member 106 to be obtained more efficiently.

[0040] As shown in FIGS. 1 and 4, the thermistor material 108 is provided in contact with the thermistor electrode 107 and is provided so as to cover at least a part of the thermistor electrode 107.

[0041] The thermistor material 108 is a material whose resistance value changes with temperature. When the membrane 104 is heated by the first heating resistive element 105 or the second heating resistive element 106, the temperature rises and the resistance value of the thermistor material 108 changes. Because the thermistor material 108 is in contact with the thermistor electrode 107, the change in the resistance value of the thermistor material 108 also changes the resistance value of the thermistor electrode 107.

[0042] As shown in Figure 4, the thermistor electrode 107 is preferably composed of two patterns 107a and 107b. To achieve a resistance value between the thermistors of the order of kΩ or more, two or more patterns may be used, with their surfaces facing each other and a gap provided. On the other hand, if the resistance value is to be the order of several hundred Ω or less, the thermistor may be composed of a single pattern without a gap.

[0043] Generally, gas sensors that use a gas heating method improve accuracy by heating the gas with a heating electrode. Thermal conduction gas sensors determine the gas concentration from the change in temperature when the gas is heated. The concentration is measured by utilizing the change in the thermal conductivity of the gas when it is heated. In this way, when the gas is heated with a heating electrode, the gas concentration can be determined by detecting the temperature change with a thermistor, and thermistors are generally used for this type of temperature detection.

[0044] As shown in Fig. 4, the thermistor electrode 107 is provided on the same plane as the second heating resistance member 106, and as described above, it can be heated by the second heating resistance member 106. However, it can also be heated by utilizing thermal conduction through the first heating resistance member 105 on the lower plane shown in Fig. 3 (Fig. 3 is a plan view showing side A of the first embodiment of the present invention in Fig. 2). In this way, the mode for efficiently heating the thermistor electrode 107 can be selected according to actual needs.

[0045] In addition, the thermistor material 108 may be provided to cover only the thermistor electrode 107, or to make manufacturing easier, it may be provided to cover both the thermistor electrode 107 and the second heating resistance member 106, or of course, it may be provided to cover the entire membrane 104 as shown in Figures 1 and 4, and those skilled in the art can select the appropriate material according to actual technical requirements.

[0046] The bonding wires 109a, 109b, and 109c in Figures 1 to 4 are wires made of materials such as gold, aluminum, and copper, and are connected using heat, ultrasound, and pressure to the pad 113a connected to the first heating resistance member 105, the pads provided at both ends of the second heating resistance member 106, and the pads provided at both ends of the thermistor electrode 107.

[0047] The other ends of the bonding wires 109a and 109b are connected to a circuit for applying a voltage for heating, and the other end of the bonding wire 109c is connected to a circuit for detecting a change in resistance of the thermistor.

[0048] FIG. 5 shows an example of a circuit for driving the first heating resistance member 105 and the second heating resistance member 106. This diagram shows that resistors 202 and 203 are connected in parallel to a voltage source 201. Resistor 202 corresponds to the resistance of the first heating resistance member 105 and the bonding wire 109a, and shows how the end of the bonding wire 109a that is not connected to the pad 113a in FIGS. 1 to 3 is connected to the circuit in FIG. 5. Meanwhile, resistor 203 corresponds to the resistance of the second heating resistance member 106 and the bonding wire 109b, and shows how the end of the bonding wire 109b that is not connected to the pads at both ends of the second heating resistance member 106 is connected to the circuit in FIG. 5 in FIGS. 1, 2, and 4.

[0049] 5, the resistor 202 of the first heating resistance member 105 is indicated as RH1, and the resistor 203 of the second heating resistance member 106 is indicated as RH2. In the first embodiment, as shown in FIGS. 3 and 4, the pattern length of the first heating resistance member 105 is longer than the pattern length of the second heating resistance member 106, and therefore RH1 is larger than RH2 due to the size of the shape.

[0050] In the circuit of FIG. 5, resistors 202 and 203 are connected in parallel and connected to voltage source 201, so that when voltage source 201 generates a voltage, the voltage is applied to resistors 202 and 203 simultaneously.

[0051] That is, the voltage generated by the voltage source 201 is applied simultaneously to the first heating resistance element 105 and the second heating resistance element 106, which causes the first heating resistance element 105 and the second heating resistance element 106 to consume power and generate heat.

[0052] 5 does not include any capacitive or inductive components, the timing of Joule heat generation is the same for the first heating resistance element 105 and the second heating resistance element 106. Furthermore, in FIG. 5, the voltage source 201 is represented by a simple pulse source symbol, but the voltage level may vary over time, or may be a sine wave, triangular wave, or PWM wave. What is important is that the first heating resistance element 105 and the second heating resistance element 106 are driven at the same timing.

[0053] To explain the derivation process of the present invention in detail, the following simulation tests will be described respectively.

[0054] 6 shows the simulation results when a voltage is applied to the first heating resistance element, and in particular shows the simulation results when the thermistor 107 and the first heating resistance element 105 are provided on the membrane 104. As described above, the first heating resistance element 105 is provided on the lower surface of the membrane 104, and the thermistor electrode 107 is provided on the upper surface of the membrane 104. In this case, when the sensor element is activated, a deformation phenomenon (downward distortion) occurs as shown on the right side of the figure.

[0055] 7 shows the simulation results when a voltage is applied to the second heating resistance element, and in particular, shows the simulation results when the thermistor electrode 107 and the second heating resistance element 106 are provided on the membrane 104. As described above, the second heating resistance element 106 and thermistor 107 are provided on the upper surface of the membrane 104, and in this case, when the sensor element is activated, a deformation phenomenon (upward distortion) occurs as shown on the right side of the figure.

[0056] From the above results, since the directions of distortion are opposite, by rationally designing the double-layered heating resistor, it is possible to cancel out the vertical deformation of each other. Figure 8 shows the simulation results when voltage is applied to the first and second heating resistors of the first embodiment. That is, the first heating resistor 105 is provided on the lower surface of the membrane 104, and the second heating resistor 106 and thermistor electrode 107 are provided on the upper surface of the membrane 104. In this case, as shown in the right part of the figure, there is basically no obvious distortion.

[0057] The actual analysis process involved a coupled analysis of electricity, heat, and thermal stress using the finite element method. First, an electrical analysis was performed. In this analysis, the flowing current and resistance values ​​of each component were calculated based on the voltage applied to the pad and the electrical resistivity and geometric parameters of the heating resistor, thermistor electrodes, thermistor material, insulator, and substrate. Next, a thermal analysis was performed. In the thermal analysis, Joule heat was calculated from the current and resistance values ​​obtained in the electrical analysis. The temperature of each component was then calculated based on the Joule heat, thermal conductivity, heat transfer coefficient, thermal radiation coefficient, and specific heat. Since the electrical resistivity of metal components changes significantly with temperature, an electrical analysis was performed again to account for this change in electrical resistivity. The flowing current and resistance values ​​of each component were then calculated based on the updated electrical resistivity and geometric parameters. The electrical and thermal analyses were then repeated until convergence was reached, and the electrical resistance, current, Joule heat, and temperature of each component were calculated. Finally, a thermal stress analysis was performed. Thermal stress was calculated from the temperature and the linear expansion coefficient, Young's modulus, and Poisson's ratio of each component, and the strain of each component was calculated.

[0058] It should be noted that the deformations in the simulation diagrams shown in FIGS. 6 to 8 are enlarged and exaggerated so that they can be easily seen.

[0059] Furthermore, if the simulation model becomes too complicated, the amount of memory required for analysis increases, making the analysis difficult. Therefore, the pad 113a is omitted from the simulation model. For the same reason, the thermistor material 108 is omitted from the simulation. (a) and (b) of FIG. 6 are views of the membrane 104 from the top. (a) of FIG. 6 shows the pattern on the top surface of the membrane 104, i.e., the thermistor electrode 107 on the top surface of the membrane 104 is shown, but the first heating resistance element 105 on the bottom surface of the membrane 104 is not shown. (b) of FIG. 6 shows only the pattern on the bottom surface of the membrane 104, i.e., only the first heating resistance element 105 is shown.

[0060] Figures 6(c) and 6(d) are diagrams showing one of the simulation results when a voltage is applied to the first heating resistance member 105. Figure 6(c) shows the deformation of the cross section taken along line A-A' in Figures 6(a) and 6(b). Figure 6(d) shows the deformation of the cross section taken along line B-B' in Figures 6(a) and 6(b).

[0061] These results show that when a meander-shaped heating resistance element is provided only on the underside of the membrane 104, the membrane 104 undergoes significant downward deformation (-z direction). This is because the first heating resistance element 105 thermally expands when heated, deforming the membrane 104. In this way, when the first heating resistance element 105 provided on the bottom of the membrane 104 thermally expands, the membrane 104 itself deforms in the -z direction.

[0062] FIG. 7 shows the simulation results when a heating resistance element is present only on the upper surface of the membrane 104. (a) and (b) of FIG. 7 are views of the membrane 104 as viewed from the top. Here, (a) of FIG. 7 shows only the pattern on the upper surface of the membrane 104, i.e., the thermistor electrode 107 and the second heating resistance element 106 on the upper surface of the membrane 104. On the other hand, (b) of FIG. 7 shows the pattern on the lower surface of the membrane 104. However, in the configuration of FIG. 7, there is no pattern on the lower surface of the membrane 104. Therefore, a description thereof will be omitted.

[0063] 7(c) and 7(d) are schematic diagrams showing the deformation of the membrane 104 and show simulation results when a voltage is applied to the second heating resistance element 106. FIG. 7(c) shows the deformation of the cross section taken along line A-A' in FIGS. 7(a) and 7(b). FIG. 7(d) shows the deformation of the cross section taken along line B-B' in FIGS. 7(a) and 7(b). These results indicate that when a meander-shaped heating resistance element is present only on the upper surface of the membrane 104, the membrane 104 undergoes significant deformation in the upward direction (+z direction). This is because the second heating resistance element 106 thermally expands upon heating, deforming the membrane 104. Thus, when the second heating resistance element 106 provided on the upper surface of the membrane 104 thermally expands, the membrane 104 itself deforms in the +z direction.

[0064] 6 and 7, it can be seen that in the configuration of Fig. 6, the meander-shaped heating resistance element is provided on the underside of the membrane 104, whereas in the configuration of Fig. 7, the meander-shaped heating resistance element is provided on the upper side of the membrane 104, resulting in a different deformation direction of the membrane 104. This is because the large expansion of the resistance element in the longitudinal direction of the meander shape is the main cause of deformation of the membrane 104.

[0065] Next, the results of a simulation based on the first embodiment shown in FIGS. 1 to 4, in which a first heating resistance member 105 and a second heating resistance member 106 are provided on the upper and lower surfaces of the membrane 104, will be described with reference to FIG. 8. FIGS. 8(a) and 8(b) are views of the membrane 104 as seen from the upper surface. Here, FIG. 8(a) shows only the pattern on the upper surface of the membrane 104, i.e., the thermistor electrode 107 and the second heating resistance member 106 on the upper surface of the membrane 104. On the other hand, FIG. 8(b) shows the pattern on the lower surface of the membrane 104, i.e., the first heating resistance member 105 on the lower surface of the membrane 104.

[0066] 8(c) and 8(d) are diagrams showing one of the simulation results when a voltage is applied to the first heating resistance element 105 and the second heating resistance element 106. FIG. 8(c) shows the deformation of the cross section taken along line A-A' in FIGS. 8(a) and 8(b). FIG. 8(d) shows the deformation of the cross section taken along line B-B' in FIGS. 8(a) and 8(b). FIG. 8 shows that the deformation of the membrane 104 was suppressed overall, but to make it easier to compare the results of FIGS. 6 to 8, a graph comparing the simulation results of FIGS. 6 to 8 was created in FIG. 9.

[0067] Figure 9 is a diagram showing changes in the upper surface of the membrane in the simulation results of Figures 6 to 8. Figure 9(a) corresponds to Figure 6(c), Figure 7(c), and Figure 8(c), and shows how the change in the z-axis direction varies depending on the position on the x-coordinate of the membrane, with the center of the membrane being x=0.

[0068] Figure 9(b) corresponds to Figures 6(d), 7(d), and 8(d), and shows how the z-axis direction changes depending on the position on the y-coordinate of the membrane, with y=0 at the center of the membrane. The solid line in Figure 9 is based on the simulation results of Figure 6. One of the dashed lines in Figure 9 is based on the simulation results of Figure 7. For comparison, the applied voltages are the same. That is, in the above simulation, the voltage applied to the first heating resistor 105 in Figure 6 is the same as the voltage applied to the second heating resistor 106 in Figure 7. The other dashed line in Figure 9 shows the simulation results of Figure 8, where the voltages applied to the first heating resistor 105 and the second heating resistor 106 in Figure 8 are the same.

[0069] In the simulation of Figure 8 in which voltage is applied to the first heating resistance element 105 and the second heating resistance element 106, power consumption and heat generation naturally increase, but deformation is smaller than in the configurations of Figures 6 and 7. This suggests that the first heating resistance element 105 and the second heating resistance element 106 attempt to deform in opposite directions, canceling out each other's displacement in the z-axis direction. In other words, the configuration of the first embodiment of the present invention can significantly reduce deformation of the membrane 104.

[0070] As explained above, by providing a first heating resistance member 105 on the underside of the membrane 104 and a second heating resistance member 106 on the upper surface of the membrane 104 and simultaneously applying voltage to the first heating resistance member 105 and the second heating resistance member 106, it is possible to reduce deformation of the membrane 104 in the z-axis direction and suppress deformation in the z-axis direction due to long-term stress and heat. This also suppresses changes in the resistance value of the thermistor due to deformation, ensuring sensor performance.

[0071] FIG. 8 shows the simulation results when voltage is applied simultaneously to the first heating resistor 105 and the second heating resistor 106. However, if the membrane 104 is made of a very thin film, voltage can be applied to only one of the first heating resistor 105 and the second heating resistor 106 to generate heat. When heat is generated, heat flow can be transmitted to the other heating resistor via the thin film, allowing both the first heating resistor 105 and the second heating resistor 106 to heat simultaneously and thermally expand simultaneously. In this way, applying voltage to only one heating resistor can heat both heating resistors, thereby generating a displacement cancellation effect. To thermally couple the first heating resistor 105 and the second heating resistor 106 and cancel each other's thermal stresses by conducting heat between them, it is preferable to keep the distance between them as short as possible. Furthermore, since the straight linear portion located at the outermost periphery of the non-linear meander portion is particularly effective in suppressing displacement of the membrane 104, in the present invention, the straight linear portion at the end of the first heating resistance member 105 and the straight linear portion at the end of the second heating resistance member 106 are made to at least partially overlap so that the thermal stress caused by the first heating resistance member 105 and the thermal stress caused by the second heating resistance member 106 cancel each other out.

[0072] 3 and 4, it is preferable that end 105a, which is a straight line at the beginning of the meander portion of first heating resistance member 105 in Fig. 3, and end 105n, which is a straight line at the end of the meander portion of first heating resistance member 105, and end 106a, which is a straight line at the beginning of the meander portion of second heating resistance member 106 in Fig. 4, and end 106n, which is a straight line at the end of the meander portion of second heating resistance member 106, are positioned so as to overlap above and below membrane 104. With this configuration, the thermal coupling between first heating resistance member 105 and second heating resistance member 106 is particularly strong at the outermost periphery of the meander portion, effectively suppressing deformation.

[0073] Furthermore, among the components of the membrane 104, the heating resistance members undergo greater thermal expansion due to heating than the other members. Therefore, the configuration and positional relationship between the first heating resistance member 105 and the second heating resistance member 106 are important in suppressing deformation of the membrane 104 in the z-axis direction. For example, in the first embodiment, the meander direction of the first heating resistance member 105 is rotated 180° relative to the meander direction of the second heating resistance member 106. While a 180° rotated configuration is used, a non-rotated configuration is preferable. This allows many of the straight portions of the meander shape to overlap at the top and bottom of the membrane 104, thereby more effectively suppressing deformation.

[0074] 3 and 4, a thermistor 107 is provided on the upper surface of the membrane 104, and the meander portion of the first heating resistance member 105 may extend to overlap the underside of this thermistor 107. If there is no pattern on the underside of the membrane 104 on which the thermistor 107 is provided, only the thermistor 107 will thermally expand due to heating, making the membrane 104 more likely to deform. However, if the first heating resistance member 105 is also present on the underside of the thermistor 107, the first heating resistance member 105 will also thermally expand, making it possible to cancel out the deformation of the thermistor 107.

[0075] While the above description focuses on deformation due to thermal stress, it is preferable to have a first heating resistance member 105 and a second heating resistance member 106 from the perspective of efficiently heating the thermistor. With this configuration, the heat generated by the first heating resistance member 105 propagates from below the thermistor, and the heat generated by the second heating resistance member 106, which is arranged planarly with respect to the thermistor, propagates from the side of the thermistor, thereby efficiently heating the thermistor. Furthermore, with this configuration, not only is deformation of the membrane 104 due to thermal stress generated in the heating resistance members reduced, but the thermistor can also be efficiently heated.

[0076] <Second embodiment> In the first embodiment, a first heating resistance member 105 is provided on the underside of the membrane 104, and a second heating resistance member 106 is provided on the upper surface of the membrane 104. When configured as in the first embodiment, it is necessary to insulate the substrate 102 from the first heating resistance member 105, so it is necessary to provide a contact surface 111 between the first heating resistance member 105 and the pad 113 and bond the first heating resistance member 105 and the pad 113 together, which complicates the manufacturing process.

[0077] Note that the first heating resistance member 105 can be easily manufactured by providing an insulating layer below the first heating resistance member 105. In this way, the first heating resistance member 105 is not provided on the lower surface of the membrane 104, but the present invention can be similarly applied to this configuration.

[0078] 10 to 13, Fig. 10 is a diagram showing a schematic structure of a second embodiment of the present invention. In the first embodiment, the first heating resistance member 105 is disposed below the membrane 104. However, in the second embodiment, the membrane includes a thermistor material 108, a thermistor electrode 107, a second heating resistance member, and a first insulator. As shown in Fig. 11, the thermistor electrode 107 is disposed on the same plane as the second heating resistance member 106, the thermistor material 108 at least partially covers the thermistor electrode 107 and the second heating resistance member 106, the first insulator 110a is disposed below the second heating resistance member 106 and partially covers the first heating resistance member 105, and the first heating resistance member 105 is disposed on the side of the first insulator 110a away from the second heating resistance member 106. Preferably, the sensor element further comprises a second insulator 110 b, which is provided below the first heating resistance member 105 .

[0079] As can be seen from the above, the first heating resistance member 105 is sandwiched between the first insulator 110a and the second insulator 110b, and therefore there is no need for a contact surface 111 between the first heating resistance member 105 and the pad 113. As the second embodiment is otherwise similar to the first embodiment in terms of configuration, a description thereof will be omitted.

[0080] FIG. 11 is a side view (-y-axis direction) of the second embodiment of the present invention. FIG. 12 is a view of plane A in FIG. 11 as viewed from above (+z-axis direction). FIG. 13 is a view of plane B in FIG. 11 as viewed from above (+z-axis direction). Note that in FIG. 13, the first heating resistance member 105 and bonding wires 109a provided below the membrane 104 are omitted to make the configuration of the upper surface of the membrane 104 easier to understand. In this case, if the first heating resistance member 105 is located below the center of the membrane 104 in the thickness direction, applying a voltage to the first heating resistance member 105 will cause the first heating resistance member 105 to expand due to Joule heat, as in the first embodiment, and cause the membrane 104 to recess in the -z direction.

[0081] Therefore, by applying a voltage to the second heating resistance member 106 at the same time as the first heating resistance member 105, it is possible to cancel out the deformation of the membrane 104, as in the first embodiment. Therefore, the first heating resistance member 105 does not necessarily have to be provided on the lower surface of the membrane 104, but may be provided below the membrane 104 in the thickness direction. A description thereof will be omitted here.

[0082] <Third embodiment> In the first and second embodiments, a configuration including the first heating resistance member 105, the second heating resistance member 106, and the thermistor electrode 107 has been described, but a configuration that can more efficiently cancel out displacement in the z-axis direction is to make the planar configuration of the first heating resistance member 105 on the membrane 104 the same as the planar configuration of the second heating resistance member 106. If the configurations of both planes are completely identical, displacement in the z-axis direction can be canceled out more effectively than in the first and second embodiments.

[0083] 14 to 18 show a third embodiment. Fig. 14 is a schematic diagram showing the structure of the third embodiment of the present invention, Fig. 15 is a side view of the third embodiment seen from the side (-y-axis direction), Fig. 16 is a view of plane A of Fig. 15 seen from above (+z-axis direction), and Fig. 17 is a view of plane B of Fig. 15 seen from above (+z-axis direction). In Fig. 17, to make it easier to understand the configuration of the upper surface of membrane 104, first heating resistance member 105 and bonding wire 109a, and second thermistor electrode 115 and bonding wire 109d provided on the underside of membrane 104 are omitted, and their description is also omitted.

[0084] The third embodiment differs from the first and second embodiments in that not only is a thermistor electrode 107 provided on the surface on which the second heating resistance member 106 is provided, but a second thermistor electrode 115 is also provided on the surface on which the first heating resistance member 105 is provided. In this configuration, it is preferable that the linear portions at the beginning and end of the meander portion of the first heating resistance member 105 and the linear portions at the beginning and end of the meander portion of the second heating resistance member 106 are configured to overlap vertically.

[0085] It is also preferable to align the gaps d2 and d1 between the second thermistor electrode 115 and the thermistor electrode 107 shown in FIGS. 16 and 17, as well as the length and pattern width of the opposing electrodes that form the gap. By using the same configuration for the thermistor electrodes above and below the membrane, as well as the heating resistors, deformation of the membrane 104 in the z-axis direction can be further suppressed. FIG. 18 is a schematic diagram showing two thermistor electrodes of the third embodiment, i.e., a circuit diagram showing the wiring of the thermistor electrode 107 and the second thermistor electrode 115. This diagram shows a circuit in which the thermistor electrode 107 and the second thermistor electrode 115 are connected in parallel. In FIG. 18, RTH1 represents the resistance 207 of the thermistor electrode 107, and RTH2 represents the resistance 208 of the second thermistor electrode 115. The combined resistance in the case of a parallel connection is calculated using the following formula (1).

number

[0086] Here, for example, if the resistance values ​​of RTH1 and RTH2 are the same, then the combined resistance R = RTH1 / 2 = RTH2 / 2. In other words, the resistance value of the combined resistance R is smaller than the resistance value of RTH1, which is also smaller than the resistance value of RTH2. This indicates that in the third embodiment, to obtain the same resistance values, the gap distance between the thermistor electrode 107 (i.e., d1 in FIG. 17) and the gap distance between the second thermistor electrode 115 (i.e., d2 in FIG. 16) may be larger than the gap distances in the first and second embodiments. Furthermore, if the gap distances d1 and d2 are too small, variations due to etching accuracy increase. Therefore, the gap distances may be larger as in the third embodiment to facilitate improved manufacturing accuracy.

[0087] As described in the first and second embodiments, the thermistor electrode 107 is configured to be in contact with the thermistor material 108. However, the second thermistor electrode 115 may or may not be provided with the thermistor material 108. By providing the thermistor material 108, the surface on which the thermistor electrode 107 is provided and the surface on which the second thermistor electrode 115 is provided have the same configuration, which improves the effect of canceling out displacement in the z-axis direction. However, since providing the thermistor material 108 complicates the manufacturing process, a person skilled in the art should select the appropriate material depending on the actual situation.

[0088] <Fourth embodiment> In the third embodiment described above, a configuration in which the second thermistor electrode 115 is provided has been described. However, in the fourth embodiment, the dummy patterns (temporary patterns) shown in FIGS. 19 to 22 are used instead of the second thermistor electrode 115. Specifically, FIG. 19 is a schematic diagram showing the configuration of the fourth embodiment. FIG. 20 is a side view of the fourth embodiment as viewed from the side (-y-axis direction). FIG. 21 is a view of surface A in FIG. 20 as viewed from above (+z direction). FIG. 22 is a view of surface B in FIG. 20 as viewed from above (+z direction). Note that FIG. 22 is a schematic diagram of surface B of the fourth embodiment of the present invention as viewed from above. Because it is a top view (plan view), components such as the first heating resistance member 105 and bonding wire 109a provided below the membrane 104 are not shown, making the configuration of the upper surface of the membrane 104 easier to understand.

[0089] As an example of the fourth embodiment, FIG. 21 shows a schematic diagram of side A of the fourth embodiment of the present invention viewed from above, illustrating an example in which a U-shaped dummy pattern 114 is provided. Without the dummy pattern 114, the thermistor electrode 107 itself would thermally expand due to heat, causing deformation of the membrane 104. Therefore, in the fourth embodiment, a dummy pattern (temporary pattern) 114 is provided on the surface of the membrane 104 opposite the thermistor electrode 107 (e.g., on the layer where the first heating resistance member 105 is located) at a position overlapping the thermistor electrode 107. In this way, the dummy pattern 114 also receives heat flow from the heating resistance member and thermally expands in the direction opposite to the thermal expansion of the thermistor electrode 107, thereby canceling out the deformation caused by the thermistor electrode 107 and suppressing deformation of the membrane 104. 21, dummy pattern 114 is shown as U-shaped, but the direction of the U-shape may be rotated 180° from the drawing. Also, it does not necessarily have to be U-shaped, and it may be an O-shape without being closed, or may be realized by two lines. By providing such dummy pattern 114, deformation of membrane 104 due to deformation of the thermistor electrode 107 can be prevented.

[0090] <Fifth embodiment> In the above description of the first embodiment, it was explained that when the membrane 104 is made of a very thin film, applying a voltage to either the first heating resistance member 105 or the second heating resistance member 106 to generate heat allows the heat flow to propagate to the other heating resistance member via the thin film, eliminating the need to apply a voltage to both heating resistance members. In order to achieve the heat propagation effect by other means, the fifth embodiment provides multiple thermal vias 116 to more effectively realize thermal coupling between the two heating resistance members.

[0091] Preferably, thermal vias 116 are provided to thermally couple the straight portions at the beginning and end of the meander portion of the first heating resistance member 105 to the straight portions at the beginning and end of the meander portion of the second heating resistance member 106, in order to enhance the degree of thermal coupling between them. The presence of the thermal vias 116 makes it possible to reliably heat both heating resistance members by heating only one of the heating resistance members. The thermal vias 116 may be provided so as to be in thermal contact with the first heating resistance member 105 and the second heating resistance member 106, but even if they are not in contact, simply bringing them close to each other will increase the degree of thermal coupling.

[0092] Figure 23 is a schematic diagram showing the configuration of a fifth embodiment of the present invention in which thermal vias are provided in the first heating resistance member and the second heating resistance member, and Figures 23 and 24 are diagrams showing an example configuration in which the first heating resistance member 105 and the second heating resistance member 106 are in contact with each other via a thermal via 116.

[0093] Specifically, Fig. 23 shows a plan view corresponding to Fig. 3 of the first embodiment, illustrating the pattern on the underside of the membrane 104. That is, the first heating resistance member 105, the pad 113a, the bonding wire 109a, and the thermal via 116 are shown. Fig. 24 shows a plan view of the fifth embodiment corresponding to Fig. 4 of the first embodiment, illustrating the pattern on the upper side of the membrane 104. That is, the second heating resistance member 106, the thermistor electrode 107, and the thermal via 116 are shown.

[0094] 23 and 24, the straight lines at the beginning and end of the meander portion of the first heating resistance member 105 and the straight lines at the beginning and end of the meander portion of the second heating resistance member 106 each contact two thermal vias 116. If the first heating resistance member 105 and the second heating resistance member 106 are in complete electrical contact via the thermal vias 116, applying a voltage to only one of the first heating resistance member 105 or the second heating resistance member 106 will cause a current to flow through the other heating resistance member, causing it to generate heat due to Joule heat. In the configurations shown in FIGS. 23 and 24, because a voltage is applied only to the first heating resistance member 105, the bonding wire on the second heating resistance member 106 side has been removed. A detailed description of this is omitted here. Even in this configuration, both the first heating resistance member 105 and the second heating resistance member 106 thermally expand due to Joule heat, so that the displacement of the membrane 104 caused by each heating resistance member can be canceled out.

[0095] Furthermore, even if the first heating resistance member 105 and the second heating resistance member 106 are not in complete contact with each other but are simply brought close to each other by the thermal via 116, the thermal coupling effect is enhanced, and the two heating resistance members are thermally expanded even when a voltage is applied to only the first heating resistance member 105 or the second heating resistance member 106. This makes it possible to cancel out the deformation of the membrane 104, meaning that there is no need to apply a voltage to both heating resistance members.

[0096] Although the present invention has been described above in terms of the first to fifth embodiments, various other application forms of the present invention are conceivable. For example, while Fig. 5 shows a configuration in which the first heating resistance element 105 and the second heating resistance element 106 are simply connected in parallel to the voltage source 201, it is necessary to apply a voltage to both heating resistance elements at the same time to heat them, and other circuit elements such as resistance elements, inductive elements, capacitive elements, and semiconductor elements may also be connected in parallel to the voltage source 201. For example, as shown in Fig. 25, which is a schematic diagram showing a circuit for driving the first heating resistance element and the second heating resistance element of the present invention, a circuit configuration including a series circuit 204 may be selected according to actual needs.

[0097] Alternatively, a bridge circuit configuration, which is often used in sensor circuits, may be used. If voltage can be applied to the resistor 202 of the first heating resistor and the resistor 203 of the second heating resistor at the same time, the effect of canceling out the deformation of the present invention can be achieved. Note that a combination of the first heating resistor 105 and the second heating resistor 106 may be included in multiple circuits. While the first and second heating resistors are configured as a two-layer structure, a multi-layer heating resistor configuration is also within the scope of protection of the present invention as long as it can achieve the cancellation effect. In other words, the terms "first" and "second" do not limit the number.

[0098] Furthermore, although voltage source 201 in Fig. 5 is shown as a simple ON / OFF pulse source, it may have a configuration in which the voltage level is switched as necessary, for example, by detecting and feeding back the outside air temperature and adjusting the voltage level. Fig. 26 is a schematic diagram of a circuit including a voltage amplifier of the present invention, and shows an example of a circuit including voltage amplifiers A1 and A2 that can apply voltages of different levels to resistor 202 of the first heating resistive element and resistor 203 of the second heating resistive element, respectively.

[0099] Furthermore, regarding the voltage, during sensor operation, the voltage applied to the first heating resistance member 105 is defined as the first voltage V1, and the voltage applied to the second heating resistance member 106 is defined as the second voltage V2, and the first voltage V1 is greater than or equal to the second voltage V2. Specifically, refer to FIG. 38 showing a graph related to an embodiment of the present invention. (a) on the left side of FIG. 38 is a graph representing the relationship between heat and position, and (b) on the right side of FIG. 38 is a graph representing the relationship between displacement and position. Each graph contains three data. Among the temperature distributions of these data, since the important one is the temperature of the detection part of the gas sensor, the voltages of V1 and V2 are adjusted so that the temperature between A and A' in (a) of FIG. 38 becomes constant. That is, in order to make the temperature between A and A' the same, it is necessary to adjust the levels of the voltage V1 applied to the first heating resistance member 105 and the voltage V2 applied to the second heating resistance member 106. Here, specifically, there are three cases: V1 < V2, V1 = V2, and V1 > V2.

[0100] As shown in (a) of FIG. 38, when V1 < V^2, excessive heating is required near - 30 μm and near 30 μm. However, excessive heating may cause damage to the gas sensor, and in the long run, it may change the characteristics of the membrane 104 due to excessive heating. Also, as shown in (b) of FIG. 38, the displacement amount when V1 < V2 is larger than the displacement amounts in other conditions. That is, when adjusted in the case of V1 = V2 or V1 > V2, the effect of keeping the corresponding temperature constant can be obtained.

[0101] In the first and second embodiments, the first heating resistance member 105 is provided below the membrane 104, and the second heating resistance member 106 and the thermistor electrode 107 are provided above the membrane 104. Conversely, the first heating resistance member 105 may be provided above the membrane 104, and the second heating resistance member 106 and the thermistor electrode 107 may be provided below the membrane 104. If the thermistor is arranged above or below the membrane 104, the thermistor can come into contact with the inflowing gas and can be operated as a gas sensor.

[0102] Furthermore, in the embodiment of the present invention, the pads of the first heating resistance member 105, the pads of the second heating resistance member 106, the pads of the thermistor electrode 107, and the pads of the second thermistor electrode 115 are arranged so as not to overlap with each other and are connected to bonding wires, but the positions of pads that are not on the membrane 104 have almost no effect on the displacement of the membrane 104 in the z-axis direction, and therefore are not limited to the configuration of this embodiment.

[0103] The present invention has been described in the first to fifth embodiments above, but for ease of understanding, various embodiments of each member of the present invention are shown in Figures 27 to 32. Figure 27 shows a first shape and structure design of each member of the present invention, in which the first heating resistance member and the second heating resistance member are located on the upper and lower layers of the membrane, and the thermistor electrode and the second heating resistance member are arranged on the same plane.

[0104] 28 shows a second structural design of each component of the present invention. In the second structural design, the membrane includes three layers. The first heating resistance element is provided in the bottom layer, i.e., the side of the membrane closest to the cavity. The second heating resistance element is provided in the middle layer, which may be configured to be the middle layer or located above the center according to actual needs. The upper layer is provided with a thermistor electrode, and the thermistor material at least partially covers the thermistor electrode. In other words, in the second structural design, the first heating resistance element, the second heating resistance element, and the thermistor electrode are arranged in different layers.

[0105] FIG. 29 shows a third shape and structure design of each member of the present invention, which differs from the first shape and structure design shown in FIG. 27 in that no pads are provided.

[0106] FIG. 30 shows a fourth shape structure design of each component of the present invention, in which the second heating resistance component and thermistor electrode are located on the upper layer, and the first heating resistance component and the second thermistor electrode are located on the lower layer.

[0107] FIG. 31 shows a fifth shape and structure design of each member of the present invention, in which a dummy pattern (temporary pattern) is introduced, and a first heating resistance member and the dummy pattern are provided in the lower layer.

[0108] 32 shows a sixth shape structure design of each component of the present invention, in which thermal vias are introduced, with the first heating resistance component and the corresponding thermal vias being provided in the lower layer, and the second heating resistance component, thermistor electrode and the corresponding thermal vias being provided in the upper layer. Each of the above-mentioned Figures 27 to 32 shows different structural designs of core components such as the first heating resistance component, the second heating resistance component, thermistor electrode, dummy pattern (temporary pattern), and thermal vias, which can be selected by those skilled in the art according to actual design requirements, and are not limited to the structural designs of the above-mentioned first to fifth embodiments and Figures 27 to 32.

[0109] Similarly, for ease of understanding, several structural designs of dummy patterns (temporary patterns) of the present invention are shown in FIGS. 33 to 37. FIG. 33 is a diagram showing a plane on which dummy patterns of a first structure of the present invention are provided, FIG. 34 is a diagram showing a plane on which dummy patterns of a second structure of the present invention are provided, FIG. 35 is a diagram showing a plane on which dummy patterns of a third structure of the present invention are provided, FIG. 36 is a diagram showing a plane on which dummy patterns of a fourth structure of the present invention are provided, and FIG. 37 is a diagram showing a plane on which dummy patterns of a fifth structure of the present invention are provided. As can be seen from FIGS. 33 to 37 above, the dummy patterns (temporary patterns) may adopt various designs, such as U-shaped, flat, O-shaped, and linear, and are of course not limited to the structural designs of FIGS. 33 to 37 above.

[0110] Another embodiment of the present invention provides a gas sensor including the sensor element described above. According to the present invention, a gas sensor can be obtained by manufacturing and combining a plurality of sensor elements 101. Also, according to the present invention, a plurality of sensor elements 101 may be provided on a single substrate 102. Since a plurality of sensor elements 101 can be provided on a single substrate 102, the sensor elements 101 can be arranged adjacent to each other, thereby reducing the mounting area. This specification is not particularly limited in this regard.

[0111] The sensor element and the gas sensor according to the embodiments of the present invention have at least one beneficial effect described below.

[0112] By combining the first heating resistance element and the second heating resistance element, the thermal stress in the thickness direction of the membrane caused by the heat generation of the first heating resistance element is in the opposite direction to the thermal stress in the thickness direction of the membrane caused by the heat generation of the second heating resistance element, so that the stresses can cancel each other out, canceling out the thermal stress in the thickness direction of the membrane and significantly reducing the thermal stress in the thickness direction of the membrane, effectively avoiding deformation of the membrane structure. As a result, the resistance characteristics of the gas sensor become stable and less likely to change, ensuring stable performance of the gas sensor.

[0113] The above-described embodiments merely specifically and in detail describe some embodiments of the present invention and do not limit the patent scope of the present invention. It should be noted that a person skilled in the art may make some modifications and improvements without departing from the spirit of the present invention, and all such modifications and improvements are within the scope of protection of the present invention. Therefore, the scope of protection of the present invention is based on the appended claims. [Industrial Applicability]

[0114] By applying the present invention, it is possible to obtain a sensor element and a gas sensor in which thermal stresses due to heating can be canceled out, deformation of the membrane structure can be avoided, and stability of the gas sensor can be ensured. The present invention can be used in the fields of sensor elements and gas sensors. [Explanation of symbols]

[0115] 101...sensor element, 102...substrate, 103...cavity, 104...membrane, 105...first heating resistance member, 105a...one end of first heating resistance member, 105n...one end of first heating resistance member, 106...second heating resistance member, 106a...one end of second heating resistance member, 106n...one end of second heating resistance member, 107...thermistor electrode, 108...thermistor material, 109a...bonding wire, 109b...bonding wire, 109c...bonding wire, 109d...bonding wire, 110...insulator, 110 a...first insulator, 110b...second insulator, 111...contact surface between first heating resistance element and pad, 112...gap, 113a...pad, 113d...pad, 114...dummy pattern (temporary pattern), 115...second thermistor electrode, 116...thermal via, 201...voltage source, 202...resistance of first heating resistance element, 203...resistance of second heating resistance element, 204...series circuit, 205...resistance of fourth heating electrode, 206...resistance of fifth heating electrode, 207...resistance of thermistor electrode, 208...resistance of second thermistor electrode.

Claims

1. A substrate; a membrane provided on the substrate, the substrate has a cavity and an opening communicating with the cavity; the membrane is supported over the opening and partially covers the cavity; the membrane includes a first heating resistance member and a second heating resistance member, the first heating resistance member and the second heating resistance member are both formed in a folded linear shape, the first heating resistance member is provided on a side of the membrane closer to the cavity portion, and the second heating resistance member is provided on a side of the membrane farther from the cavity portion; A sensor element characterized in that the straight portion of the end of the first heating resistance member and the straight portion of the end of the second heating resistance member are configured to at least partially overlap so that the thermal stresses caused by the first heating resistance member and the thermal stresses caused by the second heating resistance member cancel each other out.

2. the membrane further comprises a thermistor electrode and a thermistor material; the thermistor electrode is located on the same plane as the first heating resistance member or the second heating resistance member; 2. The sensor element according to claim 1, wherein the thermistor material at least partially covers the thermistor electrodes.

3. the membrane further comprises a thermistor electrode and a thermistor material; the first heating resistance member is provided on a side of the membrane close to the cavity, the second heating resistance member is provided on a side of the membrane farther from the first heating resistance member, the thermistor electrode is provided on a side of the membrane farther from the second heating resistance member; 2. The sensor element according to claim 1, wherein the thermistor material at least partially covers the thermistor electrodes.

4. the membrane further comprises a first thermistor electrode, a first thermistor material, and a second thermistor electrode; the first thermistor electrode is flush with the first heating resistive element, and the first thermistor material at least partially covers the first thermistor electrode; 2. The sensor element according to claim 1, wherein the second thermistor electrode is located in the same plane as the second heating resistor member.

5. 5. The sensor element of claim 4, wherein the membrane further comprises a second thermistor material, the second thermistor material at least partially covering the second thermistor electrode.

6. 3. The sensor element according to claim 2, wherein the thermistor electrode is provided inside a non-linear portion of the first heating resistance member or the second heating resistance member.

7. 2. The sensor element according to claim 1, wherein the bending direction of the non-linear portion of the first heating resistance member is rotated by 180 degrees with respect to the bending direction of the non-linear portion of the second heating resistance member.

8. 2. The sensor element according to claim 1, wherein the first heating resistance element and the second heating resistance element are connected in parallel in a circuit.

9. 9. The sensor element according to claim 8, wherein the circuit further comprises a voltage amplifier that enables adjustment of the voltage applied to the first heating resistance element and the second heating resistance element.

10. 2. The sensor element of claim 1, wherein the membrane further comprises an insulator disposed between the first heating resistance member and the second heating resistance member, and the first heating resistance member and the second heating resistance member are isolated from each other by the insulator.

11. the membrane further comprises a first insulator; the thermistor electrode is flush with the second heating resistive element, and the thermistor material at least partially covers the thermistor electrode and the second heating resistive element; 3. The sensor element according to claim 2, wherein the first insulator is provided below the second heating resistance member, the first insulator partially covers the first heating resistance member, and the first heating resistance member is provided on a side of the first insulator farther from the second heating resistance member.

12. the sensor element further comprises a second insulator; 12. The sensor element according to claim 11, wherein the second insulator is provided under the first heating resistance member.

13. 3. The sensor element according to claim 2, wherein the membrane has a dummy pattern for expanding upon application of heat to cancel out deformation caused by the thermistor electrode.

14. The sensor element of claim 1, further comprising one or more thermal vias, wherein the first heating resistance member and the second heating resistance member are thermally coupled via the thermal vias.

15. 2. The sensor element according to claim 1, wherein a voltage applied to the first heating resistance element during operation of the sensor is a first voltage, a voltage applied to the second heating resistance element is a second voltage, and the first voltage is equal to or greater than the second voltage.

16. A gas sensor comprising the sensor element according to claim 1.

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