WO2016132934A1 - Contact combustion-type gas sensor - Google Patents

Abstract

This contact combustion-type gas sensor comprises a gas reaction unit disposed in a low-thermal conductivity part and configured so as to be capable of being electrically heated, and a temperature measuring element which is formed in the low-thermal conductivity part, in the proximity of the gas reaction unit. In this contact combustion-type gas sensor, the gas reaction unit is formed from a thin catalyst film which contains a combustion catalyst of a flammable gas.

Description

Contact combustion type gas sensor

The present invention relates to a technique for reducing variation in characteristics among individuals in a contact combustion type gas sensor that detects combustible gas.
This application claims priority on February 20, 2015 based on Japanese Patent Application No. 2015-31786 for which it applied to Japan, and uses the content for it here.

Conventionally, as a gas sensor for detecting a combustible gas such as hydrogen, a catalytic combustion type gas sensor for combusting combustible gas using a catalyst and electrically detecting an increase in catalyst temperature due to combustion heat has been used. In such a catalytic combustion type gas sensor, as in various sensors, it is always required to increase detection sensitivity, and high sensitivity is achieved by various methods. For example, in Patent Document 1, in order to increase the gas detection sensitivity for low-concentration combustible gas or low-sensitivity combustible gas, the combustible gas is located near the catalyst layer that acts as a catalyst for combustion of combustible gas. It has been proposed to increase the gas detection sensitivity by forming a heater for promoting the combustion of the catalyst and forming a catalyst layer so as to cover the hot junction of the thermocouple to obtain a large sensor output.

JP 2001-99801 A

However, the catalyst layer is usually formed by applying a paste containing a carrier carrying catalyst fine particles by a dispenser, screen printing or ink jet. Therefore, the area and shape of the catalyst layer varies from individual to individual, and the relative position between the catalyst layer and the hot junction changes, so the offset (output when there is no flammable gas) varies from individual to individual sensor. In addition, the detection sensitivity of combustible gas may vary from individual to individual due to variations in catalyst layer thickness and catalyst concentration. Thus, if the characteristics vary from one individual to another, it may take time and cost to adjust the gas sensor, or the offset may fluctuate with time and measurement reproducibility may decrease.

The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a technique for reducing variation in individual characteristics in a contact combustion type gas sensor that detects combustible gas. .

In order to achieve at least a part of the above problems, a catalytic combustion type gas sensor of the present invention is provided on a low heat conduction part and configured to be electrically heatable, and on the low heat conduction part, the gas reaction part And a temperature measuring element formed in the vicinity of the gas reaction part, wherein the gas reaction part is formed of a catalyst thin film containing a combustion catalyst of combustible gas.

According to this configuration, since the catalyst thin film provided with the gas reaction part is formed by a microfabrication technique, the difference in relative position between the gas reaction part and the temperature measuring element can be further reduced. . For this reason, it is possible to further reduce variation in characteristics of each individual in the catalytic combustion type gas sensor. Moreover, since the gas reaction part is comprised so that it can be heated electrically, it becomes possible to make the activity of a combustion catalyst high and to make the detection sensitivity of combustible gas higher.

The catalyst thin film may be a metal thin film that acts as a combustion catalyst for the combustible gas. By forming the catalyst thin film with the metal thin film, the occurrence of temperature unevenness in the gas reaction part is suppressed, and the low temperature region is generated, which reduces the amount of catalytic combustion of combustible gas in the entire gas reaction part. It can suppress that the detection sensitivity of combustible gas falls.

The metal thin film may be porous. By making the metal thin film, which is a catalyst thin film, porous, the surface area where catalytic combustion occurs is increased and the amount of catalytic combustion can be increased, so that the detection sensitivity of combustible gas can be further increased.

The metal thin film may be configured to be energized, and the metal thin film may be heated by energizing the metal thin film. By energizing the metal thin film and heating the metal thin film, the temperature of the gas reaction unit can be sufficiently increased with less power, and thus the power consumption of the gas sensor can be further reduced. In addition, since the temperature of the gas reaction unit quickly rises by starting energization, it is possible to shorten the waiting time from the start of energization to the start of measurement.

The gas reaction part is formed on the low heat conduction part in the vicinity of the temperature measuring element and is in contact with the temperature measurement film provided with the temperature measurement element, and the temperature measurement on the low heat conduction part. And a separation portion that is separated from the film. According to this configuration, since the gas reaction part is separated from the temperature measuring film at the separation part, the heat generated in the gas reaction part is suppressed from being released from other than the contact part. Therefore, even when the amount of heat generated by catalytic combustion of the combustible gas in the gas reaction section is small, the temperature of the gas reaction section can be sufficiently increased, so that the detection sensitivity of the combustible gas can be further increased. .

Note that the present invention can be realized in various modes. For example, a gas sensor, a sensor module using the gas sensor, a flammable gas detection device and a flammable gas detection system using the sensor module, a leak test device and a leak using the gas sensor, the sensor module and the flammable gas detection device It can be realized in the form of a test system or the like.

Sectional drawing which shows the sensor module of 1st Embodiment of this invention. The top view which shows the sensor module of 1st Embodiment of this invention. The top view which shows the gas sensor of 1st Embodiment. FIG. 2B is a cross-sectional view taken along line AA in FIG. 2A. The top view which shows the shape of the electrically conductive film etc. in the gas sensor of 1st Embodiment. The enlarged view of R1 part of FIG. 3A. The top view which shows an example of the formation pattern of the reaction film in the gas sensor of 1st Embodiment. The top view which shows the other example of the formation pattern of the reaction film in the gas sensor of 1st Embodiment. The top view which shows the further another example of the formation pattern of the reaction film in the gas sensor of 1st Embodiment. The top view which shows the gas sensor of 2nd Embodiment of this invention. FIG. 5B is a cross-sectional view taken along line AA in FIG. 5A. Sectional drawing which shows an example of the manufacturing process after forming the electrically conductive film in the gas sensor of 2nd Embodiment of this invention. Sectional drawing which shows an example of the process after the manufacturing process shown to FIG. 6A. Sectional drawing which shows an example of the process after the manufacturing process shown to FIG. 6B.

A. First embodiment:
A1. Sensor module:
1A and 1B are diagrams showing a configuration of a catalytic combustion type gas sensor module 10 (hereinafter, also simply referred to as “sensor module 10”) in the first embodiment of the present invention.
FIG. 1A shows a cross section of the sensor module 10. In the sensor module 10 of the first embodiment, the sensor chip 100 is mounted in a package 19 including a case 11 and a cap 12. The cap 12 is made of, for example, a sintered metal such as stainless steel or brass, a wire mesh made of stainless steel, or porous ceramics. As a result, air permeability inside and outside the package 19 is secured, contamination of the sensor chip 100 is suppressed, and the sensor module 10 itself is explosion-proof. The sensor chip 100 is fixed to the case 11 by bonding the substrate 110 provided with the cavity 119 to the case 11 with the die bonding material 15.

FIG. 1B shows a state where the sensor chip 100 fixed to the case 11 is viewed from above. 1B is a cutting line indicating the position of the cross section shown in FIG. 1A. Also, alternate long and short dash lines C1 and C2 are center lines indicating the center position of the sensor chip 100.
As shown in FIG. 1B, bonding pads P11 to P15 with exposed conductive films are formed on the upper surface of the sensor chip 100. By connecting the bonding pads P11 to P15 and the terminal 14 connected to the external electrode 13 of the case 11 with a wire 16 (wire bonding), the sensor chip 100 and the external circuit can be connected.
As shown in FIG. 1B, the gas sensor 100 includes a center line C1 extending in the horizontal direction in FIG. 1B (hereinafter simply referred to as “horizontal direction”) and a vertical direction in FIG. 1B (hereinafter simply referred to as “vertical direction”). It is formed substantially symmetrically with respect to the center line C2 extending in the so-called “e”). Therefore, in the following, unless there is a necessity, only one of such symmetrical portions will be described.

The sensor chip 100 includes a gas detection unit RD1 above the center line C1 and a compensation unit RC1 below the center line C1 in FIG. 1B. A gas reaction part 191 is formed on the upper surface of the gas detection part RD1 with the conductive film exposed. Since this gas reaction part 191 is the surface of the exposed conductive film itself, it can also be said that it is formed of a conductive film.
Although details will be described later, in the gas sensor 100, the combustible gas that has passed through the cap 12 and reached the sensor chip 100 is formed by forming the conductive film using a metal that acts as a combustion catalyst for the combustible gas. In the gas reaction unit 191, catalytic combustion occurs, and an amount of heat corresponding to the concentration of the combustible gas is generated. Therefore, the temperature of the gas reaction unit 191 increases according to the concentration of the combustible gas. On the other hand, since the gas reaction unit 191 is not provided in the compensation unit RC1, a temperature increase due to catalytic combustion does not occur.
The sensor chip 100 outputs signals representing the temperatures of the conductive member (reaction film) provided with the gas reaction unit 191 and the conductive member (reference film) provided in the compensation unit RC1 corresponding to the reaction film. To do. Based on these output signals, external factors such as changes in environmental temperature are obtained by determining the temperature difference between the reaction membrane that rises in temperature due to catalytic combustion of combustible gas and the reference membrane that does not rise in temperature due to combustible gas. It is possible to compensate for fluctuations in output with high accuracy and to measure the concentration of combustible gas in the atmosphere with high accuracy.
Thus, since the sensor chip 100 has a function of detecting gas in the sensor module 10, it can be said that the sensor chip 100 is a gas sensor itself. Therefore, hereinafter, the sensor chip 100 is simply referred to as “gas sensor 100”.
In order to suppress the temperature rise due to the catalytic combustion of the combustible gas in the region other than the reaction membrane, after wire bonding, epoxy resin or the like is potted in the region of the bonding pads P11 to P15 by using a dispenser or the like to act as a combustion catalyst. It is preferred to eliminate metal exposure. Also, in the step of forming a conductive film constituting the reaction film (described later), the metal in the region of the bonding pads P11 to P15 is replaced with aluminum (Al) or an Al alloy, or burned against combustible gas. It is also possible to cover the surface of the metal acting as a catalyst with Al or an Al alloy so as to eliminate the exposure of the metal acting as a combustion catalyst in the region of the bonding pads P11 to P15.

A2. Gas sensor:
2A and 2B are diagrams showing the configuration of the gas sensor 100. FIG. FIG. 2A shows the gas sensor 100 as viewed from above, and FIG. 2B shows a cross section of the gas sensor 100 taken along the cutting line AA in FIG. 2A.

The gas sensor 100 includes a substrate 110 provided with a cavity 119, an insulating film 120 formed on the upper surface of the substrate 110, and a mask film 101 formed on the lower surface of the substrate 110 and provided with an opening 109. Yes. On the insulating film 120, a plurality of films (functional films) forming a structure (described later) for realizing a gas detection function are stacked. Specifically, the n-type semiconductor film 130, the first interlayer insulating film 140, the p-type semiconductor film 150, the second interlayer insulating film 160, the conductive film 170, and the protection are formed on the insulating film 120. The film 180 is laminated in this order.
Among these functional films, the n-type and p-type semiconductor films 130 and 150, the first and second interlayer insulating films 140 and 160, the conductive film 170, and the protective film 180 are used as a method for manufacturing a semiconductor device. It can be formed using a known technique. Note that the insulating film 120, the mask film 101, and each functional film stacked on the insulating film 120 are appropriately added or omitted depending on the contents of the manufacturing process.

In the manufacturing process of the gas sensor 100, first, a silicon (Si) substrate having no cavity 119 is prepared. Next, the insulating film 120 is formed by depositing silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), and SiO ₂ in this order on the upper surface of the prepared Si substrate. A mask film (not shown) having no opening 109 is formed on the lower surface of the Si substrate by depositing SiO ₂ and Si ₃ N ₄ in this order in accordance with the formation of the insulating film 120. Note that the insulating film 120 and the mask film may be a single layer film of silicon oxynitride (SiON) instead of a multilayer film of SiO ₂ and Si ₃ N ₄ .

After the formation of the insulating film 120, an n-type semiconductor film 130 is formed by depositing and patterning n-type polysilicon. As a material for forming the n-type semiconductor film 130, various semiconductors such as iron silicide (FeSi ₂ ), silicon-germanium (SiGe), or bismuth antimony (BiSb) may be used instead of polysilicon. After the n-type semiconductor film 130 is formed, SiO ₂ is formed to form a first interlayer insulating film (not shown) that is not patterned.
Next, a p-type semiconductor film 150 is formed by depositing and patterning p-type polysilicon. Similarly to the n-type semiconductor film 130, the p-type semiconductor film 150 can be formed using various semiconductors other than polysilicon. In addition, the conductivity types of these two semiconductor films 130 and 150 can be reversed. After the formation of the p-type semiconductor film 150, SiO ₂ is formed, and the formed SiO ₂ film and the unpatterned first interlayer insulating film are patterned, whereby the first interlayer insulating film 140 and the first interlayer insulating film 140 are formed. Two interlayer insulating films 160 are formed.

After the first and second interlayer insulating films 140 and 160 are formed, platinum (Pt) is formed and patterned to form the conductive film 170. As a material for forming the conductive film 170, various metals (catalyst metals) that function as a combustion catalyst for combustible gas such as palladium (Pd), Pt, and an alloy of Pd can be used instead of Pt. .
The conductive film 170 may be formed as a multilayer film in which various metals that do not function as a combustion catalyst (non-catalytic metal) and a catalytic metal are stacked as long as the upper surface is formed of a catalytic metal. For example, an adhesion layer made of titanium (Ti) or chromium (Cr) may be formed on the lower surface of the conductive film 170. Further, in the conductive film 170, the reaction film provided with the gas reaction part 191 is formed of a catalytic metal such as Pt, and the other part is tungsten (W), tantalum (Ta), gold (Au), copper (Cu). It is also possible to form a non-catalytic metal such as nickel (Ni), Al or Al alloy.
After the formation of the conductive film 170, the protective film 180 is formed by depositing and patterning SiO ₂ . As shown in FIGS. 2A and 2B, the protective film 180 has five openings 181 to 185 for forming bonding pads PD1 to PD5 (FIGS. 1A and 1B) and an opening 189 for forming a gas reaction part 191. In these openings 181 to 185 and 189, the conductive film 170 is exposed.

After the formation of the protective film 180, a cavity 119 provided in the substrate 110 is formed. When forming the cavity 119, first, an opening 109 is formed in the mask film formed on the lower surface side of the substrate. Next, the cavity 119 is formed by etching the substrate using the mask film 101 provided with the opening 109 as a mask. Etching can be performed by, for example, crystal anisotropic etching using an aqueous solution of tetramethylammonium hydroxide (TMAH) or potassium hydroxide (KOH). In addition to such wet etching, the cavity may be formed by dry etching such as a so-called Bosch process. By etching the substrate to form the cavity 119, the membrane 121 with the insulating film 120 exposed on the back surface side is formed.
Since the cavity 119 formed on the lower surface of the membrane 121 is difficult to transfer heat, it can be referred to as a low thermal conduction portion. On the other hand, since the substrate 110 easily transfers heat to the outside of the gas sensor 100 such as the case 11 (FIG. 1A), it can be said to be a high thermal conductivity portion.

In the example of FIGS. 2A and 2B, the cavity 119 is formed by etching the substrate from the lower surface side, but the cavity can also be formed by etching the substrate from the upper surface side. In this case, a cavity can be formed by providing a through hole in the insulating film 120, the first and second interlayer insulating films 140 and 160, and the protective film 180 and etching the substrate through the through hole. . When the substrate is etched from the upper surface side in this way, the gas sensor can be manufactured only by processing from the upper surface side of the substrate, and the remaining portion of the substrate can be increased compared to the case where the remaining portion is etched from the lower surface side. Therefore, it is preferable to etch the substrate from the upper surface side in that the manufacturing process of the gas sensor can be simplified to increase the yield, and the strength of the substrate after etching can be further increased. On the other hand, etching from the lower surface side of the substrate can form a cavity without providing a through hole in the insulating film 120, so that the strength of the through hole formed in the membrane is suppressed and the membrane is damaged. It is preferable at the point which can suppress.

The hollow portion is not necessarily provided in the substrate. For example, a cavity can be formed between the substrate 110 and the insulating film 120 or between the insulating film 120 and the n-type semiconductor film 130 and the first interlayer insulating film 140. In such a cavity on the substrate, after forming a sacrificial film in a region where the cavity on the substrate or the insulating film 120 is formed, each functional film up to the protective film is formed as described above, and then the upper surface of the protective film is formed. The through hole reaching the sacrificial film is provided, and the sacrificial film is removed through the through hole.
As a material for forming the sacrificial film, a resin such as polyimide or a semiconductor such as polysilicon can be used. The sacrificial film made of resin can be removed by ashing, and the sacrificial film made of semiconductor can be removed by etching. However, in the case where a semiconductor is used as the sacrificial film, in order to prevent the etching of the substrate or the n-type semiconductor film, the substrate or the insulating film 120 and the sacrificial film are made of blocking such as SiO ₂ or Si ₃ N _4. A film is formed.
Thus, when the cavity is formed on the substrate, the strength of the substrate can be made higher than when the substrate is etched. On the other hand, the substrate is preferably etched in that the manufacturing process of the gas sensor can be further simplified.

3A and 3B are diagrams showing a functional configuration of the gas sensor 100. FIG. FIG. 3A shows a state where the gas sensor 100 is viewed from the top, as in FIG. 2A. FIG. 3B is an enlarged view of a region R1 surrounded by a two-dot chain line in FIG. 3A. 3A and 3B, the protective film 180 is not hatched for convenience of illustration.

In the gas sensor 100, a structure for realizing a gas detection function is formed by the n-type semiconductor film 130, the p-type semiconductor film 150, and the conductive film 170 shown in FIGS. 2A and 2B. That is, the n-type semiconductor film 130 (FIGS. 2A and 2B) is connected to the n-type thermoelectric element 131, the two heaters 132 and 133 formed in a narrow and narrow line shape, and the heaters 132 and 133, respectively. Connection lines 134 and 135 are formed. A p-type thermoelectric element 151 is formed by the p-type semiconductor film 150 (FIGS. 2A and 2B). The conductive film 170 (FIGS. 2A and 2B) forms a hot junction connection line 171, a cold junction connection line 172, a signal output electrode 173, a thermopile connection line 174, a heater energization electrode 175, a ground wiring 176, a reaction film 177, and a reference film 178. Is done. Further, by providing openings 181 to 185 in the protective film 180 (FIGS. 2A and 2B), bonding pads (signal output pads) P11 and P13 from which the signal output electrode 173 is exposed and bonding pads from which the heater energizing electrode 175 is exposed are provided. (Heater energization pads) P12 and P14 and bonding pads (ground pads) P15 where the ground wiring 176 is exposed are formed. Further, as described above, the gas reaction part 191 is formed by providing the opening 189 in the protective film 180 and exposing the reaction film 177.
3A and 3B, the heaters 132 and 133 and the heater connection lines 134 and 135 are formed of the n-type semiconductor film 130. However, at least the heaters 132 and 133 and the heater connection lines 134 and 135 are not provided. One of the conductive films 170 can be formed. Further, in order to improve the shielding property against electromagnetic noise, an opening may be provided in the insulating film 120 and the first and second interlayer insulating films 140 and 160 to connect the ground wiring 176 and the substrate 110. .

In the gas sensor 100 of the first embodiment, a plurality of n-type thermoelectric elements 131 extending in the horizontal direction are arranged in the vertical direction, and the first interlayer insulating film 140 (FIGS. 2A and 2B) of the n-type thermoelectric element 131 is interposed therebetween. A p-type thermoelectric element 151 shorter than the n-type thermoelectric element 131 is formed at the upper position. The first and second interlayer insulating films 140 and 160 are arranged at both end portions of the n-type thermoelectric element 131 where the p-type thermoelectric element 151 is not formed on the first and second interlayer insulating films 140 and 160. Contact holes H11 and H12 penetrating 160 are provided. The second interlayer insulating film 160 is provided with contact holes H13 and H14 penetrating the second interlayer insulating film 160 at the positions of both ends of the p-type thermoelectric element 151.

The hot junction connection line 171 connects the n-type thermoelectric element 131 and the p-type thermoelectric element 151 which are stacked vertically with the first interlayer insulating film 140 interposed therebetween via the contact holes H11 and H13. On the other hand, the cold junction connection line 172 connects the adjacent n-type thermoelectric element 131 and p-type thermoelectric element 151 through the contact holes H12 and H14. Thus, the n-type thermoelectric element 131, the p-type thermoelectric element 151, the hot junction connection line 171 and the cold junction connection line 172 constitute a thermopile T11 in which a plurality of thermocouples having hot junctions and cold junctions are connected in series. The thermopiles T12 to T14 are configured in the same manner as the thermopile T11.

The thermopile connection line 174 further connects in series the thermopile T11 and T12 in which thermocouples are connected in series. The signal output electrode 173 is connected to the p-type thermoelectric element 151 at one end of the thermopiles T11 and T12 connected in series via the contact hole H14. On the other hand, the n-type thermoelectric element 131 at the other end of the thermopiles T11 and T12 connected in series is connected to the ground wiring 176 through the contact hole H12. The thermopiles T13 and T14 are also connected in the same manner as the thermopiles T11 and T12. As a result, a voltage corresponding to the temperature difference between the hot and cold junctions of the thermopiles T11 and T12 is generated at the signal output pad P11 of the gas detection unit RD1 with respect to the ground pad P15, and the signal output of the compensation unit RC1 The pad P13 has a voltage corresponding to the temperature difference between the hot junction constituted by the hot junction connection line 171 of the thermopile T13 and T14 and the cold junction constituted by the cold junction connection line 172 with respect to the ground pad P15. appear.

4A, 4B, and 4C are explanatory diagrams illustrating examples of formation patterns of the reaction film 177. FIG. 4A shows a formation pattern of the reaction film 177 and the hot junction connection line 171 formed in the vicinity of the reaction film 177 in the first embodiment, and FIGS. 4B and 4C show the reaction films 877 and 977 and the reaction. The modification of the formation pattern with the hot-junction connection line 871,971 formed in the vicinity of the film | membranes 877 and 977 is shown.
As shown in FIG. 4A, the reaction film 177 of the first embodiment is formed so as to surround the hot junction connection line 171 and to form a narrow gap SP1 between the hot junction connection line 171. The reaction film 177 and the hot junction connection line 171 are both formed of a conductive film 170 having high thermal conductivity. Therefore, heat is transferred well between the reaction film 177 and the hot junction connection line 171, and in the region including the reaction film 177 provided with the gas reaction portion 191 and the hot junction connection line 171, the heat is concerned. Dispersed over the entire area, the temperature is made uniform. In this manner, in the region including the reaction film 177 and the hot junction connection line 171, heat is dispersed throughout the region, and the temperature is uniformized.

In the example of FIG. 4B, the reaction film 877 is formed in a substantially circular shape, and the shape of the gas reaction part 891 is changed in accordance with the shape of the reaction film 877. Other points are the same as those of the first embodiment shown in FIG. 4A. Therefore, also in the example of FIG. 4B, the reaction film 877 substantially surrounds the hot junction connection line 871, and the gap SP8 between the reaction film 877 and the hot junction connection line 871 is sufficiently narrow. In a region including 877 and the hot junction connection line 871, heat is dispersed throughout the region, and the temperature is made uniform.

In the example of FIG. 4C, since the hot junction connection line 971 extends in the center direction of the reaction film 977, the conductive film is continuous in the vertical direction in the central portion of the region including the reaction film 977 and the hot junction connection line 971. Absent. However, also in the case of FIG. 4C, the gap SP9 between the reaction film 977 and the hot junction connection line 971 is narrow, so that heat transfer between the reaction film 977 and the hot junction connection line 971 is improved. can do. Therefore, in the region including the hot junction connection line 971 and the reaction film 977, heat is dispersed throughout the region, and the temperature is made uniform.
Furthermore, in the example of FIG. 4C, a part of the hot junction connection line 971 is exposed, and the gas reaction part 991 is also provided in the exposed part. Therefore, heat generated by catalytic combustion at the exposed portion of the hot junction connection line 971 is directly transmitted to the hot junction, so that the detection sensitivity of the combustible gas can be further increased.

4A, 4B, and 4C show a state in which the soaking part is formed from the reaction films 177, 877, 977 and the hot junction connection lines 171, 871, 971, the cold junction connection line is shown. A heat equalizing member can be formed by the conductive film 170 in the same pattern in the vicinity of 172 (FIGS. 3A and 3B). In this case, since the uniformity of the temperature of the cold junction is higher, the measurement accuracy of the gas concentration can be further increased. In order to further increase the temperature uniformity of the cold junction, openings are provided in the insulating film 120 and the first and second interlayer insulating films 140 and 160 to connect the heat equalizing member and the substrate 110. Also good.

As shown in FIG. 4A, the hot junction connection line 171 constituting the hot junction in the gas detection unit RD1 is disposed in a soaking part including a reaction film 177 having a gas reaction unit 191 and a hot junction connection line 171. Yes. Similarly, the hot junction connection line 171 constituting the hot junction in the compensation unit RC1 (FIGS. 3A and 3B) is disposed in a soaking part including the reference film 178 and the hot junction connection line 171.
On the other hand, as shown in FIGS. 3A and 3B, the cold junction connection line 172 constituting the cold junction in the gas detection unit RD1 and the compensation unit RC1 is disposed on the substrate 110. Therefore, the temperature of the reaction film 177 and the reference film 178 can be measured based on the substrate 110 or the case 11 (FIGS. 1A and 1B) having substantially the same temperature as the substrate 110.
As described above, the hot junctions of the thermopiles T11 to T14 can measure the temperatures of the reaction film 177 and the reference film 178, and can also be referred to as temperature measuring elements. In the examples of FIGS. 3A and 3B and FIGS. 4A, 4B, and 4C, the hot junction constituted by the hot junction connection line 171 is formed in the soaking part including the reaction film 177 or the reference film 178, respectively. In general, the hot junction may be formed in the vicinity of each of the reaction film 177 and the gas reaction part 191 provided in the reaction film 177 and the reference film 178. That is, the temperature measuring element is formed on the cavity portion 119 (low heat conduction portion) and in the vicinity of the gas reaction film 191. For example, the reaction membrane and the reference membrane can be provided only between the thermopiles TP11 to TP14 arranged in the lateral direction. Even in this case, the temperature of the reaction film and the reference film can be measured using the thermopile TP11 to TP14.
Similarly, the cold junction of the thermopile only needs to be formed in the vicinity of the substrate 110. As can be seen from the above description, the reaction film 177, the gas reaction part 191 and the reference film 178 are each formed in a region including the vicinity of the temperature measuring element (that is, the hot junction of the thermopiles T11 to T14). It only has to be.

As shown in FIGS. 3A and 3B, the heater 132 provided in the gas detector RD1 is disposed between the thermopiles T11 and T12, and the heater connection lines 134 and 135 connected to the heater 132 are heater energizing electrodes, respectively. 175 and the ground wiring 176 are extended. These heater connection lines 134 and 135 are connected to the heater energizing electrode 175 and the ground wiring 176 via contact holes H15 and H16 provided in the first and second interlayer insulating films 140 and 160 (FIGS. 2A and 2B). It is connected. Therefore, the heater 132 can be energized by applying a voltage between the heater energization pad P12 and the ground pad P15. The heater 133 provided in the compensation unit RC1 can be energized by applying a voltage between the heater energizing pad P14 and the ground pad P15.

When the heater 132 is energized, the reaction film 177 formed on the heater 132 is heated, and the temperature of the reaction film 177 rises. Thereby, the activity of the reaction film 177 as a combustion catalyst is increased, and the catalytic combustion of the combustible gas in the gas reaction unit 191 is promoted, so that the detection sensitivity of the combustible gas in the gas sensor 100 is increased. When hydrogen gas (H ₂ ) is detected as a combustible gas, water (H ₂ O) is generated by catalytic combustion in the gas reaction unit 191. At this time, if the temperature of the reaction film 177 is low, the generated H ₂ O condenses, so that the surface of the gas reaction unit 191 may be wetted and the detection sensitivity may be lowered. In the gas sensor 100 according to the first embodiment, the reaction film 177 is heated by the heater 132, thereby suppressing a decrease in detection sensitivity due to the generated H ₂ O.
Further, the reference film 178 can be heated by the heater 133 similarly to the reaction film 177, and the heating temperature can be controlled independently of the heater 132. Therefore, when the flammable gas is not included in the atmosphere, the reaction film 177 and the reference film 178 are set to substantially the same temperature, the voltage signal output from the thermopiles T11 and T12 of the gas detection unit RD1, and the thermopile T13 of the compensation unit RC1. The difference (offset) from the voltage signal output from T14 can be made substantially zero. Note that the heater 133 provided under the reference film 178 may be omitted. However, since the offset can be further reduced, it is preferable to provide the heater 133 below the reference film 178.

Further, as shown in FIGS. 3A and 3B, the hot contact connection line 171, the heaters 132 and 133, the reaction film 177, and the reference film 178 constituting the hot contacts of the thermopiles T11 to T14 are formed on the membrane 121. Since the membrane 121 is generally formed thin (about 1 to 5 μm), the membrane 121 itself has a small heat capacity and is mainly composed of an insulating film (SiO ₂ , Si ₃ N ₄ ) having low thermal conductivity. Therefore, the transfer of heat in the direction along the membrane 121 is suppressed. A hollow portion 119 that does not transmit heat is formed on the lower surface of the thin membrane 121. Therefore, even when the amount of heat generated by the catalytic combustion of the combustible gas in the gas reaction unit 191 is small, the temperature of the gas reaction unit 191 can be sufficiently increased, so that the detection sensitivity of the combustible gas in the gas sensor 100 is further increased. Can be high.

In the gas sensor 100 according to the first embodiment, in the gas detection unit RD1, since the soaking part (the hot junction connection line 171 and the reaction film 177) having high thermal conductivity is disposed on the upper part of the heater 132, it is generated in the heater 132. The heat is dispersed throughout the soaking part in the soaking part. Therefore, since the occurrence of temperature unevenness in the gas reaction unit 191 is suppressed, the generation of a low temperature region reduces the catalytic combustion amount of the combustible gas in the entire gas reaction unit 191 and the gas detection sensitivity decreases. Can be suppressed. Further, in the compensation unit RC1 in addition to the gas detection unit RD1, the temperature equalizing unit (the hot junction connection line 171 and the reference film 178) having high thermal conductivity is disposed above the heater 133, so that the temperature in the membrane 121 is increased. The symmetry of the distribution can be increased. Therefore, the compensation of the external factor using the compensation unit RC1 can be performed with sufficiently high accuracy, so that an increase in offset and an increase in offset change (drift) due to environmental temperature, gas flow rate, etc. are suppressed, and low The concentration gas can be detected more easily, and the measurement reproducibility of the gas concentration can be increased.

Further, the hot junction connection line 171 that forms the hot junction, the reaction film 177 that determines most of the outer shape of the soaking part (the hot junction connection line 171 and the reaction film 177), and the gas reaction part 191 Since it is formed by a patterning technique used in a semiconductor manufacturing process such as lithography, the accuracy of the position of the hot junction with respect to the soaking part and the gas reaction part 191 can be increased. Therefore, the characteristics of the gas sensor 100 such as offset, drift, or sensitivity can be suppressed from varying for each individual gas sensor 100. In the present specification and the present invention, a film formed by chemical vapor deposition (CVD), sputtering, vapor deposition, or the like, like the reaction film 177, is formed by a microfabrication technique for patterning by photolithography or the like. The member is called a thin film. Moreover, what was formed with the metal among such a thin film is called a metal thin film.

In the first embodiment, the reference film 178 is formed in order to compensate for a temperature change due to an external factor of the reaction film 177 (gas reaction unit 191). However, in order to simplify the manufacturing process, the reference film 178 is formed. Can be omitted. In this case, the hot junction constituted by the hot junction connection line 171 in the compensation unit RC1 only needs to be formed in the vicinity of the heater 133 so as to measure the temperature of the heater 133 whose temperature is close to the gas reaction unit 191. . However, the reference film 178 is made in that the heat capacities of the regions where the reaction film 177 and the reference film 178 are formed can be made closer to each other, and the deterioration of the detection accuracy of the combustible gas due to the influence of the airflow or the like can be suppressed. Preferably formed.

In the first embodiment, the gas reaction part 191 is formed by providing the opening 189 in the protective film 180 and exposing a part of the reaction film 177, but the combustible to be detected is formed on the upper surface of the gas reaction part 191. It is also possible to form a permselective membrane that selectively permeates the property gas. In this case, since the catalytic metal forming the reaction membrane 177 can be prevented from being poisoned by the permselective membrane, it is possible to suppress a decrease in the detection sensitivity of the combustible gas due to the poisoning.

B. Second embodiment:
B1. Gas sensor configuration:
5A and 5B are diagrams showing the configuration of the gas sensor 200 according to the second embodiment of the present invention. FIG. 5A shows the gas sensor 200 as viewed from above, and FIG. 5B shows a cross section of the gas sensor 200 along the cutting line A shown in FIG. 5A.
In the gas sensor 200, a part of the exposed reaction film 291 and the reference film 296 is brought into contact with the lower functional film, and the other part is floated in the air. Further, in the gas sensor 200, the soaking films 236 and 237 are formed instead of the heaters 132 and 133 in the gas sensor 100 (FIGS. 3A and 3B) of the first embodiment, the heater connecting lines 134 and 135 are omitted, and the reaction film The 291 and the reference film 296 are configured to be heated by direct energization.
On the other hand, in the gas sensor 200 of the second embodiment, portions related to the thermopile are produced in the same manner as the gas sensor 100 of the first embodiment, and the configuration is similar. Therefore, in parts related to the thermopile, parts similar to the gas sensor 100 are denoted by reference numerals obtained by changing the first numerals assigned to the respective parts of the gas sensor 100 from “1” to “2”, and description thereof is omitted. To do.
In the second embodiment, since the conductive film 270 does not need to function as a combustion catalyst, it can be formed of a non-catalytic metal such as Al or an Al alloy instead of Pt. As a material for forming the conductive film 270, patterning can be performed by photolithography using reactive ion etching, plasma etching, or wet etching, and fine processing with high accuracy and high yield is easy. 200
It is preferable to use Al or an Al alloy in that it can be manufactured more easily.

The reaction film 291 is connected to plate-like power feeding portions 292 and 293 provided at both ends in the lateral direction of the membrane 221. Further, the reaction film 291 is in contact with the second interlayer insulating film 260 at the contact portion 294 on the center line C2. A soaking film 236 formed of the n-type semiconductor film 230 is disposed at a position below the contact portion 294 with the first and second interlayer insulating films 240 and 260 interposed therebetween.
The reaction film 291 and the power feeding parts 292 and 293 are formed of a catalytic metal such as Pt. Thereby, since the reaction film 291 functions as a combustion catalyst for combustible gas, the entire reaction film 291 can be referred to as a gas reaction part.
Similarly to the reaction film 291, the power supply parts 297 and 298 are connected to the reference film 296, and the first and second interlayer insulating films 240 and 260 of the contact part 299 included in the reference film 296 are sandwiched therebetween. A soaking film 237 is disposed at the position. The reference film 296 and the power feeding parts 297 and 298 are formed of a non-catalytic metal such as Ni. Further, the reference membrane 296 and the power feeding units 297 and 298 can be formed of a metal that selectively functions as a combustion catalyst with respect to a specific combustible gas. In this case, the gas sensor 200 is used to detect a gas other than the specific combustible gas.
The reaction film 291 and the reference film 296 are provided with through holes HA for easier processing in a process (described later) for floating portions other than the contact portions 294 and 299 in the air.

The power feeding units 292 and 293 connected to the reaction film 291 are provided on the upper surfaces of the heater connection line 277 connected to the heater energization electrode 275 and the heater connection line 278 connected to the ground wiring 276, respectively. Therefore, the reaction film 291 can be energized by applying a voltage between the heater energizing electrode 275 on the gas detection unit RD2 side and the ground wiring 276. Similarly, the power feeding portions 297 and 298 connected to the reference film 296 are provided on the upper surfaces of the heater connection line 277 connected to the heater energization electrode 275 and the heater connection line 278 connected to the ground wiring 276, respectively. ing. Therefore, the reference film 296 can be energized by applying a voltage between the heater energizing electrode 275 and the ground wiring 276 on the compensator RC2 side.

In the gas detection part RD2, the contact part 294 of the reaction film 291 and the soaking film 236 are disposed in the vicinity of the hot junction connection line 271 constituting the hot junction. In the compensation unit RC2, the contact portion 299 of the reference film 296 and the soaking film 237 are disposed in the vicinity of the hot junction connection line 271 that constitutes the hot junction.
On the other hand, in the gas detection unit RD <b> 2 and the compensation unit RC <b> 2, the cold junction connection line 272 constituting the cold junction is disposed on the substrate 210. For this reason, the signal output electrode 273 of the gas detection unit RD2 and the compensation unit RC2 has the reaction film 291 and the reference film 296 based on the substrate 210 or the case 11 (FIGS. 1A and 1B) at substantially the same temperature as the substrate 210, respectively. The voltage corresponding to the temperature is output. Therefore, output fluctuations due to external factors such as changes in environmental temperature can be compensated with high accuracy, and the concentration of combustible gas in the atmosphere can be measured with high accuracy.
In the second embodiment, it is also possible to form a soaking film with the conductive film 270 in the same shape as the reaction film 177 (FIGS. 4A, 4B, and 4C) of the first embodiment. In this way, the temperature of the hot junction connection line 271 can be made closer to the temperature of the reaction membrane 291 and the reference membrane 296, so that combustible gas can be detected with higher sensitivity.

Also in the gas sensor 200 of the second embodiment, since the temperature of the reaction film 291 can be increased by energizing the reaction film 291, the detection sensitivity of combustible gas can be further increased, and H ₂ or the like can be detected. A decrease in detection sensitivity can be suppressed. The reference film 296 can be heated by energization in the same manner as the reaction film 291, and the heating temperature can be controlled independently of the reaction film 291. Therefore, when the atmosphere does not contain a flammable gas, refer to the reaction film 291. It is possible to set the temperature of the film 296 to substantially the same temperature and the offset to substantially zero.
Further, in the gas sensor 200, the area of the reaction film 291 can be increased, and combustible gas is catalytically combusted on both the upper surface and the lower surface of the reaction film 291. For this reason, the area of the catalytic combustion area is increased, and the amount of heat generated by catalytic combustion can be increased, so that the detection sensitivity of the combustible gas can be further increased.

Furthermore, in the gas sensor 200, the reaction film 291 and the reference film 296 are formed of a metal having high thermal conductivity. In addition, the entire reaction film 291 and the reference film 296 generate heat due to energization. Therefore, occurrence of temperature unevenness in the reaction film 291 can be suppressed, and a decrease in gas detection sensitivity can be suppressed. Moreover, since the symmetry of the temperature distribution in the membrane 221 can be increased, an increase in offset and drift can be suppressed, gas detection at a low concentration can be facilitated, and measurement reproducibility of the gas concentration can be increased. Is possible.

Also in the second embodiment, as shown in FIGS. 5A and 5B, the hot junction connection line 271 constituting the hot junction and the contact portion 294 of the reaction film 291 are formed on the membrane 221. Further, since the reaction film 291 is floated in the air except for the contact part 294, the heat generated in the reaction film 291 is suppressed from being released from other than the contact part 294. Therefore, even when the amount of heat generated by the catalytic combustion of the combustible gas in the reaction film 291 is small, the temperature of the reaction film 291 can be sufficiently increased, so that the detection sensitivity of the combustible gas in the gas sensor 200 is further increased. be able to.
Note that the n-type and p-type semiconductor films 230 and 250, the first and second interlayer insulating films 240 and 260, and the conductive film 270 as a whole include a hot junction that is a temperature measuring element. It can also be referred to as a temperature measuring film on which is formed. As is clear from the above description, the contact portion 294 of the reaction film 291 is in contact with the temperature measuring film in the vicinity of the temperature measuring element. Further, the portion of the reaction film 291 that floats in the air is separated from the temperature measurement film, and thus can be referred to as a separation part.

The hot junction connection line 271 forming the hot junction, the contact portions 294 and 299 of the reaction film 291 and the reference film 296, and the soaking films 236 and 237 are formed by a patterning technique used in a semiconductor manufacturing process such as photolithography. Since it is formed, the accuracy of the position of the hot junction with respect to the contact portions 294 and 299 and the soaking films 236 and 237 can be increased. Therefore, the characteristics of the gas sensor 200 such as offset, drift, or sensitivity can be suppressed from varying for each gas sensor 200.

In the gas sensor 100 according to the second embodiment, soaking heat from the contact portions 294 and 299 to the hot junction connection line 271 is provided, soaking films 236 and 237 are provided under the contact portions 294 and 299. However, these soaking films 236 and 237 can be omitted. In addition to the soaking films 236 and 237, a soaking film may be formed by the p-type semiconductor film 250 under the contact portions 294 and 299, and only the soaking film formed by the p-type semiconductor film 250 may be formed. It is also possible to arrange.

B2. Gas sensor manufacturing process:
6A, 6B, and 6C are process diagrams illustrating an example of a manufacturing process of the gas sensor 200 after the conductive film 270 is formed. 6A to 6C show cross-sections of the intermediate products 200a to 200c in each step along the cutting line A shown in FIG. 5A.
Similar to the first embodiment, after forming the insulating film 220 and the mask film 201 on the upper surface and the lower surface of the Si substrate 210a, respectively, the n-type semiconductor film 230, the first interlayer insulating film 240, and the p-type semiconductor film are formed. By forming the second interlayer insulating film 260 and the conductive film 270, the intermediate product 200a shown in FIG. 6A is obtained.

Next, a photosensitive resin such as polyimide is applied to the upper surface of the intermediate product 200a and patterned to obtain an intermediate product 200b having a sacrificial film 280 formed on the upper surface of the intermediate product 200a as shown in FIG. 6B. The sacrificial film 280 is provided with through holes 281, 282, and 283 above the soaking films 236 and 237 (FIGS. 5A and 5B) and the heater connection lines 277 and 278, respectively.

After the formation of the sacrificial film 280, a catalyst metal is formed on the upper surface of the intermediate product 200b on the gas detection unit RD2 side, and a non-catalytic metal is formed on the upper surface of the intermediate product 200b on the compensation unit RC2 side. The catalytic metal or the non-catalytic metal formed on the upper surface of the intermediate product 200b contacts the second interlayer insulating film 260 through the through hole 281 and is connected to the heater connection lines 277 and 278 through the through holes 282 and 283. . Thereby, the contact portions 294 and 299 (FIGS. 5A and 5B) are provided for the catalytic metal and the non-catalytic metal, and the power feeding portions 292 and 293 made of the catalytic metal and the power feeding portions 297 and 298 made of the non-catalytic metal ( 5A and 5B) are formed.
Next, by patterning the catalytic metal and the non-catalytic metal, a reaction film 291 and a reference film 296 (FIGS. 5A and 5B) having a desired outer shape and having a through hole HA are formed (FIG. 6C). As in the first embodiment, the substrate 210a of the intermediate product 200c obtained in this manner is etched by using the mask film 201 provided with the opening 209 (FIGS. 5A and 5B) as a mask. It is formed. After the formation of the cavity 209, the sacrificial film 280 is removed by ashing, whereby the gas sensor 200 (FIGS. 5A and 5B) of the second embodiment is obtained.

C. Variations:
The present invention is not limited to the above embodiment, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

C1. Modification 1:
In each of the above embodiments, the reaction film provided with the gas reaction part is formed of a thin film made of a catalyst metal, that is, a metal thin film that acts as a catalyst. However, the reaction film can be formed of various thin films including a combustion catalyst. For example, a film (catalyst dispersion film) in which a catalyst metal such as Pt and a matrix material such as SiO ₂ , Si ₃ N _4, or SiON are simultaneously sputtered (co-sputtering) and a cluster of catalyst metals is dispersed in the matrix material It is also possible to form the catalyst dispersion film by patterning. In this case, the reference film can be formed by patterning a film formed by sputtering a matrix material alone or a film formed by co-sputtering a matrix material and a non-catalytic metal. In addition, since the metal thin film and catalyst dispersion film used as a reaction film are thin films containing a combustion catalyst, they can also be called catalyst thin films.

When the catalyst thin film is formed of a metal thin film, it is preferable to form a large number of pores in the metal thin film from the viewpoint that the surface area can be increased to increase the amount of catalytic combustion, and the detection sensitivity of the combustible gas can be increased. Such a metal thin film is obtained by, for example, patterning a film formed by co-sputtering a catalyst metal and a pore forming material that is selectively etched with respect to the catalyst metal, and forming a patterned film pore forming material. It can be formed by selective etching.

C2. Modification 2:
In the first embodiment, the reaction film 177 and the gas reaction part 191 are heated by the heater 132. However, as in the second embodiment, the reaction film 177 and the gas reaction part 191 are turned on by energizing the reaction film 177. Direct heating may be used. Generally, by energizing the reaction membrane provided with the gas reaction unit and heating the reaction membrane, the temperature of the gas reaction unit can be sufficiently increased with less power, so the power consumption of the gas sensor can be further increased. It can be reduced. In addition, since the temperature of the reaction film and the gas reaction part is quickly increased by starting energization, the waiting time until the measurement is started can be shortened.

C3. Modification 3:
In each of the above-described embodiments, a thermopile configured by connecting n-type and p-type thermoelectric elements with a hot junction connection line and a cold junction connection line is used. It is also possible to use a thermopile configured by replacing at least one of the n-type and p-type thermoelectric elements in this configuration with a metal thermoelectric element. In this case, since the metal thermoelectric element can be formed at the same time as the conductive film, an increase in the number of steps for manufacturing the gas sensor can be suppressed. When both n-type and p-type thermoelectric elements are replaced with metal thermoelectric elements, the two metal thermoelectric elements are formed of different metals. However, it is preferable to use two types of semiconductors having different conductivity types as the thermoelectric element in that the thermoelectromotive force in the thermopile can be increased and the sensitivity of the gas sensor can be further increased.

C4. Modification 4:
In each of the above embodiments, a thermopile in which a plurality of thermocouples are connected in series is used to measure the temperatures of the reaction membrane (gas reaction section) and the reference membrane. However, the temperature of the reaction film and the reference film can be measured using other temperature measuring elements such as a single thermocouple, a resistance temperature detector, or a thermistor. However, a thermopile in which a plurality of thermocouples are connected in series is used in that a sufficiently high voltage signal representing the temperature of the reaction membrane and the reference membrane is output and the detection sensitivity of the combustible gas can be further increased. preferable.

C5. Modification 5:
In each of the above embodiments, the gas sensor is provided with the gas detection unit and the compensation unit, but the compensation unit may be omitted. In this case, in a state where there is no flammable gas, after sufficient time has elapsed since the heating of the reaction film has started, by adjusting the offset so that the output voltage becomes 0 using an operational amplifier or the like, Detection of combustible gas can be performed.

C6. Modification 6:
In each of the embodiments described above, a cavity provided in the substrate itself or a cavity formed on the substrate is used as the low thermal conduction part. However, the low thermal conduction part is not necessarily a cavity.
The low heat conductive part can be formed, for example, by embedding a heat insulating material such as a porous material or a resin in a cavity provided in the substrate itself. When SiO ₂ is used as the porous material, the porous SiO ₂ can be embedded in the cavity by a known technique of forming a low relative dielectric constant (Low-k) insulating film or silica airgel. When a resin is used as the porous material, the monomer or prepolymer of the resin is filled in the cavity, and then the monomer or prepolymer is polymerized by heat or ultraviolet rays.
Moreover, you may form heat insulation films, such as a porous material and resin, on a board | substrate as a low heat conductive part. In this case, in the same manner as the step of forming the cavity on the substrate described above, a heat insulating film such as a porous material or a resin is formed on the substrate or the insulating film 120, and the formed heat insulating film is left to leave the low heat conducting portion. Can be formed. Further, a polysilicon film for forming a heat insulating film may be formed on the substrate, and the polysilicon film may be made porous by anodic oxidation.
Furthermore, you may form a porous part in board | substrate itself as a low heat conductive part. For example, when a Si substrate is used as the substrate, the porous portion is a region corresponding to the cavity from the lower surface side of the substrate or the upper surface side of the substrate, as in the step of forming the cavity portion in the substrate itself. It can be formed by making it porous by anodization.
In the case of using a low thermal conduction part that is not a cavity, if the material of the low thermal conduction part is conductive, an insulating film is added between the low thermal conduction part and the semiconductor film or the conductive film. As described above, the use of the low thermal conductive portion that is not a cavity suppresses the breakage of the functional film formed on the low thermal conductive portion.

DESCRIPTION OF SYMBOLS 10 ... Sensor module 11 ... Case 12 ... Cap 13 ... External electrode 14 ... Terminal 15 ... Die bond material 16 ... Wire 100, 200 ... Gas sensor 101, 201 ... Mask film | membrane 109,209 ... Opening part 110,210,210a ... Substrate 119, 209 ... Cavity 120, 220 ... Insulating films 121, 221 ... Membranes 130, 230 ... n-type semiconductor films 131, 231 ... n-type thermoelectric elements 132, 133 ... heaters 134, 135 ... heater connection wires 140, 160, 240, 260 ... interlayer insulating films 150, 250 ... p-type semiconductor films 151, 251 ... p-type thermoelectric elements 170, 270 ... conductive films 171, 271, 871, 971 ... hot junction connection lines 172, 272 ... cold junction connection lines 173, 273 ... Signal output electrodes 174, 274 ... Thermopile connection lines 175, 275 ... Heater energizing electrode 1 6,276 ... Ground wirings 177, 877, 977 ... Reaction film 178 ... Reference film 180 ... Protective films 181-185,189 ... Opening 19 ... Packages 191,891,991 ... Gas reaction parts 200a, 200b, 200c ... Intermediate products 236, 237 ... soaking films 277, 278 ... heater connection lines 280 ... sacrificial films 281, 282, 283 ... through holes 291 ... reaction films 292, 293, 297, 298 ... power feeding parts 294, 299 ... contact parts 296 ... reference films H11 to H16 ... contact holes HA ... through holes P11 and P13 ... signal output pads P12 and P14 ... heater energization pads P15 ... ground pads RC1, RC2 ... compensation parts RD1, RD2 ... gas detection parts SP1, SP8, SP9 ... gap T11 ~ T14 ... Thermopile

Claims (6)

A contact combustion type gas sensor for detecting a combustible gas,
A gas reaction part provided on the low heat conduction part and configured to be electrically heated;
A temperature measuring element formed in the vicinity of the gas reaction part on the low heat conduction part,
With
The gas reaction part is a catalytic combustion type gas sensor formed by a catalyst thin film containing a combustion catalyst of the combustible gas. The catalytic combustion gas sensor according to claim 1, wherein the catalyst thin film is a metal thin film that acts as a combustion catalyst for the combustible gas. 3. The catalytic combustion type gas sensor according to claim 2, wherein the metal thin film is porous. 4. The catalytic combustion type gas sensor according to claim 2, wherein the metal thin film is configured to be energized, and the metal thin film is heated by energizing the metal thin film. The gas reaction part is formed on the low heat conduction part in the vicinity of the temperature measuring element and is in contact with the temperature measurement film provided with the temperature measurement element, and the temperature measurement on the low heat conduction part. The catalytic combustion type gas sensor according to any one of claims 1 to 4, further comprising a separation portion that is separated from the membrane. The catalytic combustion type gas sensor according to claim 2, wherein a plurality of pores are formed in the metal thin film.

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